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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Mar. 12, 2018	Sep. 29, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	CLXT
Entity Registrant Name	CALYXT, INC.
Entity Central Index Key	0001705843
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		28,062,315
Entity Public Float			$ 135,919,500

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 56,664	$ 5,026
Trade accounts receivable	0	110
Due from related parties	167	47
Prepaid expenses and other current assets	626	282
Total current assets	57,457	5,465
Property and equipment, net	14,353	10,994
Other long-term assets	357	164
Total assets	72,167	16,623
Current liabilities:
Due to related parties	1,350	1,712
Accounts payable	1,023	357
Accrued salaries, wages, and other compensation	945	332
Accrued liabilities	893	363
Deferred revenue	43	101
Total current liabilities	4,254	2,865
Non-current deferred revenue	289	639
Financing lease obligation	10,148
Total liabilities	14,691	3,504
Stockholders' equity:
Common stock, $0.0001 par value; 275,000,000 shares authorized, 27,718,780 and 19,600,000 shares issued and outstanding as of December 31, 2017 and 2016, respectively	3	2
Preferred stock, $0.0001 par value; 50,000,000 shares authorized, no shares issued or outstanding as of December 31, 2017 and 2016, respectively
Additional paid-in capital	112,021	41,685
Accumulated deficit	(54,548)	(28,568)
Total stockholders' equity	57,476	13,119
Total liabilities and stockholders' equity	$ 72,167	$ 16,623

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	275,000,000	275,000,000
Common stock, shares issued	27,718,780	19,600,000
Common stock, shares outstanding	27,718,780	19,600,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 508	$ 399	$ 1,272
Operating expenses:
Cost of revenue		200	751
Research and development	11,556	5,638	2,766
Selling, general and administrative	14,741	6,670	3,569
Total Operating expenses	26,297	12,508	7,086
Loss from operations	(25,789)	(12,109)	(5,814)
Interest expense	(1)	(5)	(261)
Foreign currency transaction (loss) gain	(190)	28	186
Loss before income taxes	(25,980)	(12,086)	(5,889)
Income tax expense	0	0	0
Net loss	$ (25,980)	$ (12,086)	$ (5,889)
Basic and diluted loss per share	$ (1.12)	$ (0.62)	$ (0.88)
Weighted average shares outstanding-basic and diluted	23,153,661	19,600,000	6,725,740

Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2014	$ (10,436)		$ 47	$ (10,483)
Beginning balance, shares at Dec. 31, 2014		2,450,000
Capital contributed to Parent	40,000	$ 2	39,998
Capital contributed to Parent, shares		17,150,000
Dividend to parent	(110)			(110)
Stock-based compensation	692		692
Net loss	(5,889)			(5,889)
Ending balance at Dec. 31, 2015	24,257	$ 2	40,737	(16,482)
Ending balance, shares at Dec. 31, 2015		19,600,000
Stock-based compensation	948		948
Net loss	(12,086)			(12,086)
Ending balance at Dec. 31, 2016	13,119	$ 2	41,685	(28,568)
Ending balance, shares at Dec. 31, 2016		19,600,000
Issuance of common stock	57,980	$ 1	57,979
Issuance of common stock, shares		8,050,000
Stock options exercised	$ 265		265
Stock options exercised, shares	68,780	68,780
Stock-based compensation	$ 12,092		12,092
Net loss	(25,980)			(25,980)
Ending balance at Dec. 31, 2017	$ 57,476	$ 3	$ 112,021	$ (54,548)
Ending balance, shares at Dec. 31, 2017		27,718,780

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (25,980)	$ (12,086)	$ (5,889)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	551	345	147
Stock-based compensation	12,092	948	692
Changes in operating assets and liabilities:
Trade accounts receivable	110	107	25
Due to/from related parties	(482)	1,702	(1,265)
Prepaid expenses and other assets	(537)	(387)	59
Accounts payable	665	53	(28)
Accrued salaries, wages and other compensation	613	88	93
Accrued liabilities	591	137	40
Deferred revenue	(408)	(144)	(565)
Net cash used in operating activities	(12,785)	(9,237)	(6,691)
Investing activities
Purchases of property and equipment	(779)	(10,424)	(665)
Net cash used in investing activities	(779)	(10,424)	(665)
Financing activities
Proceeds from common stock issuance	61,292
Costs incurred related to the issuance of stock	(3,312)
Capital contribution from Parent			30,000
Advances from Parent	3,000		2,050
Repayment of advances from Parent	(3,000)		(200)
Dividend to Parent			(110)
Proceeds from the exercise of stock option	265
Cash received for land and other improvements as a part of the financing lease obligation	6,957
Net cash provided by financing activities	65,202		31,740
Net increase (decrease) increase in cash and cash equivalents	51,638	(19,661)	24,384
Cash and cash equivalents-beginning of period	5,026	24,687	303
Cash and cash equivalents-end of period	56,664	5,026	24,687
Supplemental cash flow information
Interest paid	200	$ 5	$ 261
Supplemental non-cash investing and financing transactions
Property and equipment included in financing lease obligation	$ 3,130

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Calyxt, Inc., formerly known as Cellectis Plant Sciences, Inc. (the Company or Calyxt), was founded in 2010 and incorporated in Delaware. The Company is headquartered in New Brighton, Minnesota. Calyxt is a consumer-centric, food- and agriculture-focused company. The Company changed its name from Cellectis Plant Sciences, Inc. to Calyxt, Inc. on May 4, 2015. Prior to the Company’s initial public offering (IPO) on July 25, 2017, Calyxt was a wholly owned subsidiary of Cellectis S.A. (“Cellectis” or “Parent”). As of December 31, 2017, Cellectis owned approximately 79.7% of the Company’s outstanding common stock. Calyxt’s common stock is listed on the Nasdaq market under the ticker symbol “CLXT”. *Initial Public Offering* On July 25, 2017, the Company completed an IPO of its common stock, in which it sold an aggregate of 8,050,000 shares of its common stock at a price of $8.00 per share, including 1,050,000 shares of common stock pursuant to the exercise of the underwriters’ option to purchase additional shares. In the aggregate, the Company received net proceeds from the IPO and exercise of the overallotment of approximately $58.0 million, after deducting underwriting discounts and commissions of $3.1 million and offering expenses totaling approximately $3.3 million. As part of the IPO, Cellectis purchased 2,500,000 shares of the Company’s common stock for a value of $20.0 million, which is included in the net proceeds of approximately $58.0 million. The Company used $5.7 million of the proceeds from Cellectis to pay a portion of the outstanding obligations owed to Cellectis. *Stock Splits* On June 14, 2017, pursuant to the authorization provided in a written consent in lieu of a special meeting of the Company, the Company effected a stock split of the Company’s common stock at a ratio of 100-for-1 and increased the number of shares of common stock authorized for issuance to 30,000,000 by filing a Certificate of Amendment with the Secretary of State of the State of Delaware. On July 25, 2017, the Company amended its Amended and Restated Certificate of Incorporation to increase the authorized capital stock of the Company to 325,000,000 shares of which 275,000,000 shares are designated common stock, par value $0.0001, and 50,000,000 shares are designated preferred stock, par value $0.0001. On July 25, 2017, concurrently with the closing of the IPO, the Company effected a stock split of the Company’s common stock at a ratio of 2.45-for-1. As a result of the stock split, each share of issued and outstanding common stock was converted into 2.45 shares of issued and outstanding common stock without changing the par value per share. Since the par value of the common stock remained at $0.0001 per share subsequent to each stock split, the value of common stock recorded to the Company’s balance sheets has been retroactively increased to reflect the par value of the increased number of outstanding shares, with a corresponding decrease to additional paid-in capital. All share and per share data for periods occurring prior to the stock split that are included in the financial statements and related notes have been retroactively restated to reflect the stock splits.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to stock-based compensation and the valuation allowance for deferred tax assets and derivatives. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash and cash equivalents consist of cash and term deposits with original maturities of three months or less. The carrying value of these instruments approximate fair value. The balances, at times, may exceed federally insured limits. The Company has not experienced any losses on its cash and cash equivalents.

Trade Accounts Receivable

Accounts receivable are unsecured, are recorded at net realizable value, and do not bear interest. The Company makes judgments as to its ability to collect outstanding receivables based upon patterns of collectability, historical experience, and management’s evaluation of specific accounts and will provide an allowance for credit losses when collection becomes doubtful. The Company performs credit evaluations of its customers’ financial condition on an as-needed basis. Payment is generally due 30 days from the invoice date, and accounts past 30 days are individually analyzed for collectability. When all collection efforts have been exhausted, the account is written off against the related allowance.

As of December 31, 2017, the Company had no trade accounts receivables.

Prepaid Expenses and Other Current Assets

Other current assets represent prepayments, R&D tax credits receivable and deposits made by the Company.

Property and Equipment

Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed based upon the estimated useful lives of the respective assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life of the assets. Repairs and maintenance costs are expensed as incurred. The cost and accumulated depreciation of property and equipment retired, or otherwise disposed of, are removed from the related accounts, and any residual values are charged to expense. Depreciation expense has been calculated using the following estimated useful lives:


Buildings and other improvements		10–20 years
Leasehold improvements		Remaining lease period
Office furniture and equipment		5–7 years
Computer equipment and software		3–5 years

Leases

Leases are classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. In September 2017, the Company entered into a financing lease. Refer to Note 11 for more detail.

Long-Lived Assets

The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. If the impairment tests indicate that the carrying value of the asset, or asset group is greater than the expected undiscounted cash flows to be generated by such asset or asset group, further analysis is performed to determine the fair value of the asset or asset group. To the extent the fair value of the asset or asset group is less than its carrying value, an impairment loss is recognized equal to the amount the carrying value exceeds the fair value of the asset or asset group. Assets to be disposed of are carried at the lower of their carrying value or fair value less costs to sell.

There have been no impairment losses recognized for the years ended December 31, 2017, 2016 or 2015.

Fair Value of Financial Instruments

Pursuant to the requirements of Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement, the Company’s financial assets and liabilities measured at fair value on a recurring basis are classified and disclosed in one of the following three categories:

Level 1—Financial instruments with unadjusted quoted prices listed on active market exchanges.

Level 2—Financial instruments lacking unadjusted, quoted prices from active market exchanges, including over-the-counter traded financial instruments. The prices for the financial instruments are determined using prices for recently traded financial instruments with similar underlying terms, as well as directly or indirectly observable inputs, such as interest rates and yield curves that are observable at commonly quoted intervals.

Level 3—Financial instruments that are not actively traded on a market exchange. This category includes situations in which there is little, if any, market activity for the financial instrument. The prices are determined using significant unobservable inputs or valuation techniques.

The Company has derivative instruments that are classified as Level 2. The Company does not have any financial instruments classified as Level 3, and there were no movements between these categories during the years ended December 31, 2017, 2016 or 2015.


	Fair Value Measurements at December 31, 2017 (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	3		—	$	3

Total Assets at Fair Value		—	$	3		—	$	3

Liabilities at Fair Value
Forward purchase contracts		—	$	4		—	$	4

Total Liabilities at Fair Value		—	$	4		—	$	4


	Fair Value Measurements at December 31, 2016, (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	9		—	$	9

Total Assets at Fair Value		—	$	9		—	$	9

Liabilities at Fair Value
Forward purchase contracts		—	$	19		—	$	19

Total Liabilities at Fair Value		—	$	19		—	$	19

Forward Purchase Contracts and Derivatives

The Company enters into supply agreements for grain and seed production with settlement values based on commodity market futures pricing. The Company accounts for these derivative financial instruments utilizing the authoritative guidance in ASC Topic 815, Derivatives and Hedging. Realized gains and losses from derivative contracts are recorded as research and development expenses as a result of breeding contract activity. The fair value for forward purchase contracts is estimated based on exchange-quoted prices.

Unrealized gains and losses on all derivative contracts are recorded in other current assets or other current liabilities on the balance sheet at fair value. The gains and losses recorded by the Company are not significant for the years ended December 31, 2017, 2016 or 2015.

The table below summarizes the carrying value of derivative instruments as of December 31, 2017, 2016 and 2015.


	Asset Derivatives					Liability Derivatives
Derivatives not designated as hedging instruments under ASC Topic 815		Fair Value						Fair Value
	Balance Sheet Location	December 31, 2017		December 31, 2016		Balance Sheet Location		December 31, 2017		December 31, 2016
		(expressed in thousands)						(expressed in thousands)
Forward purchase contracts	Prepaid expenses & other current assets	$	3	$	9		Accrued liabilities—current	$	4	$	19

Total derivatives		$	3	$	9			$	4	$	19

Patents

The Company expenses patent costs, including related legal costs, as incurred. Costs to write, maintain, in-license, and defend patents are recorded as selling, general and administrative expenses in the statements of operations. Costs to support the research for filing patents are recorded as research and development expenses in the statements of operations.

Revenue Recognition

The Company enters into R&D agreements that may consist of nonrefundable up-front payments, milestone payments, royalties, and R&D Services. In addition, the Company may license its technology to third parties, which may be part of the R&D agreements.

For agreements that contain multiple elements, each element within a multiple-element arrangement is accounted for as a separate unit of accounting provided the following criteria are met: the delivered products or services have value to the customer on a stand-alone basis and, for an arrangement that includes a general right of return relative to the delivered products or services, delivery, or performance of the undelivered product or service is considered probable and is substantially controlled by the Company. The Company considers a deliverable to have stand-alone value if the product or service is sold separately by the Company or another vendor or could be resold by the customer. Further, the Company’s revenue arrangements do not include a general right of return relative to the delivered products.

Nonrefundable up-front payments are deferred and recognized as revenue over the period of the R&D agreement. If an R&D agreement is terminated before the original term of the agreement is fulfilled, all the remaining deferred revenue is recognized at the date of termination.

Milestone payments represent amounts received from the Company’s R&D partners, the receipt of which is dependent upon the achievement of certain scientific, regulatory, or commercial milestones. The Company recognizes milestone payments when the triggering event has occurred, there are no further contingencies or services to be provided with respect to that event, and the counterparty has no right to refund of the payment. The triggering event may be scientific results achieved by the Company or another party to the arrangement, regulatory approvals, or the marketing of products developed under the arrangement.

Royalty revenue arises from the Company’s contractual entitlement to receive a percentage of product sales revenues achieved by counterparties. Royalty revenue is recognized on an accrual basis in accordance with the terms of the agreement when sales can be determined reliably and there is reasonable assurance that the receivables from outstanding royalties will be collected.

License revenue from licenses that were granted to third parties is recognized ratably over the period of the license agreements. Revenue from R&D services is recognized over the period the R&D services are performed. No new revenue arrangements were entered in the year.

Cost of Revenue

Cost of revenue relates to the performance of services or contract research and consists of direct external expenses relating to projects and internal costs, including overhead allocated on a full-time equivalent basis.

Research and Development

R&D expenses represent costs incurred for the development of various products using licensed gene editing technology, including expenses allocated to the Company by Cellectis. R&D expenses consist primarily of salaries, stock compensation and related costs of the Company’s scientists, in-licensing of technology, consumables, property and equipment depreciation, and fees paid to third-party consultants. All research and development costs are expensed as incurred, totaling $11.6 million, $5.6 million and $2.8 million for the years ended December 31, 2017, 2016 and 2015, respectively.

The Company in-licenses certain technology from third-parties that is a component of ongoing research and product development. The Company expenses up-front license fees upon contracting due to the uncertainty of future commercial value, as well as expensing any ongoing annual fees when incurred. Related-party in-licensing expense was $93 thousand, $44 thousand and $86 thousand for the year ended December 31, 2017, 2016 and 2015, respectively. Third-party in-licensing expenses were $447 thousand, $539 thousand and $165 thousand for the year ended December 31, 2017, 2016 and 2015, respectively.

Stock Based Compensation

The Company measures employee and nonemployee stock-based awards at grant-date fair value and records compensation expense using the accelerated attribution method over the vesting period of the award. Stock-based awards issued to nonemployees are remeasured until the award vests. The Company uses the Black-Scholes option pricing model to value its stock option awards. Estimating the fair value of stock option awards requires management to apply judgment and make estimates, including the volatility of the Company’s common stock, the expected term of the Company’s stock options, the expected dividend yield and the fair value of the Company’s common stock on the measurement date. The Company accounts for forfeitures as they occur, rather than estimating expected forfeitures.

The expected term of stock options is estimated using the “simplified method” for employee options as the Company has no historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is based on the average of the vesting tranches and the contractual life of each grant. For options granted to nonemployees, the Company uses the remaining contractual life. For stock price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The Company assumes no dividend yield because dividends are not expected to be paid in the near future, which is consistent with the Company’s history of not paying dividends. The risk-free interest rate is based on U.S. Treasury notes with a term approximating the expected life of the option.

Foreign Currency Transactions

Transactions in foreign currencies are remeasured into the Company’s functional currency, U.S. dollars, at the exchange rates effective at the transaction dates. Assets and liabilities denominated in foreign currencies at the reporting date are remeasured into the functional currency using the exchange rate effective at that date. The resulting exchange gains or losses are recorded in the statements of operations under selling, general, and administrative expenses.

Income Taxes

Current income taxes are recorded based on statutory obligations for the current operating period for the jurisdictions in which the Company has operations.

Deferred taxes are provided on an asset and liability method, whereby deferred tax assets are recognized for deductible temporary differences and deferred tax liabilities are recognized for taxable temporary differences. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax basis. Deferred tax assets are reduced by a valuation allowance when the Company believes it is more likely than not that some portion or all of the deferred tax assets will not be realized. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment.

The tax effects from an uncertain tax position can be recognized in the financial statements only if the position is more likely than not to be sustained on audit, based on the technical merits of the position. The Company recognizes the financial statement benefit of a tax position only after determining that the relevant tax authority would more likely than not sustain the position following an audit. For tax positions meeting the more-likely than-not threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50% likelihood of being realized upon settlement with the relevant tax authority. The Company is subject to income taxes in U.S. federal and state jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal and state income tax examinations by tax authorities for years ending prior to 2013. In the event of any future tax assessments, the Company’s accounting policy is to record the income taxes and any related interest or penalties as current income tax expense on the statements of operations.

Recently Adopted Accounting Pronouncements

In November 2015, the FASB issued Accounting Standards Update (ASU) 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The amendment simplifies the presentation of deferred income taxes. Instead of separating deferred income tax liabilities and assets into current and non-current amounts in a classified statement of financial position, the amendments in this update require that deferred tax liabilities and assets be classified as non-current in a classified statement of financial position. For public entities, ASU 2015-17 is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. For non-publicentities, ASU 2015-17 is effective for annual periods beginning after December 15, 2017, and interim periods within annual periods beginning after December 15, 2018. Adoption of this standard did not have a material impact on the Company’s financial statements as all net deferred tax assets are fully reserved.

In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. This ASU eliminates the additional paid-in capital (APIC) pool concept and requires that excess tax benefits and tax deficiencies be recorded in the statement of operations when awards are settled. The ASU also addresses simplifications related to statement of cash flows classification, accounting for forfeitures, and minimum statutory tax withholding requirements. For public entities, ASU 2016-09 is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. For all other entities, ASU 2016-09 is effective for annual periods beginning after December 15, 2017, and interim periods within annual periods beginning after December 15, 2018. Early adoption is permitted. The Company adopted this standard in the second quarter of 2017, as a result of adoption, the Company recognized an $813 thousand tax benefit as a reduction of income tax expense, however, due to full valuation allowance, the net impact is zero.

Recently Issued Accounting Pronouncements

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which creates ASC Topic 606, Revenue from Contracts with Customers, and supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition. The guidance in ASU 2014-09 and subsequently issued amendments ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net); ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing; and ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients, outlines a comprehensive model for all entities to use in accounting for revenue arising from contracts with customers, as well as required disclosures. Entities have the option of using either a full retrospective or modified approach to adopt the new guidance. For public entities, certain not-for-profit entities, and certain employee benefit plans, the new revenue standard is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. For all other entities, the new revenue standard is effective for annual periods beginning after December 15, 2018, and interim periods within annual periods beginning after December 15, 2019. Early adoption is permitted. The adoption of this standard is not expected to have a material effect on the Company.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The guidance requires that lessees recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than 12 months. The amendment also requires disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative information. For public entities, not-for-profit entities, or employee benefit plans, ASU 2016-02 is effective for annual periods beginning after December 15, 2018, and interim periods within those annual periods. For all other entities, ASU 2016-02 is effective for annual periods beginning after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Early adoption is permitted. The Company is evaluating the impact of adopting this pronouncement.

In May 2017, the FASB issued ASU 2017-09, “Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting”, which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact of adopting this standard on the financial statements and disclosures, but does not expect it to have a significant impact.

Concentrations of Credit Risk	12 Months Ended
Concentrations of Credit Risk	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	3. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents, and trade accounts receivable. The Company also has concentrations of revenue with certain customers. Cash and cash equivalents concentration—The Company holds cash balances at financial institutions that, at times, may exceed federally insured limits. The Company evaluates the creditworthiness of these financial institutions in determining the risk associated with these deposits. The Company has not experienced any losses on such accounts. Trade accounts receivable concentration—As of December 31, 2017, the Company had no trade accounts receivable. As of December 31, 2016, one customer accounted for 100% of trade accounts receivable. As of December 31, 2015, two customers accounted for 50% each of the trade accounts receivable. Revenue concentration—For the year ended December 31, 2017, three customers accounted individually for 51.0%, 40.6% and 6.7% of revenue, respectively. In 2016, four customers accounted individually for 33%, 28%, 19% and 16% of revenue, respectively. In 2015, three customers accounted individually for 38%, 26% and 20% of revenue, respectively.

Property and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment

4. Property and Equipment

Property and equipment for the years ended December 31, 2017 and 2016 consists of the following:


(Amounts in thousands)	2017			2016
Land	$	5,690		$	5,690
Buildings and other improvements		4,414			4,304
Leasehold improvements		169			169
Office furniture and equipment		1,672			1,506
Computer equipment and software		20			20
Assets under construction		3,671			37

		15,636			11,726
Less accumulated depreciation		(1,283	)		(732	)

Property and equipment, net	$	14,353		$	10,994

As of December 31, 2017, the Company recorded $3,671 thousand in assets under construction which consists of the phase two construction costs (related to the sale-leaseback transaction, site improvements and architect fees) and lab equipment for our new headquarters facility. At the completion of construction, the completed asset will be capitalized and depreciated over the term of the lease.

Depreciation expense was $551 thousand, $345 thousand and $147 thousand for the year ended December 31, 2017, 2016 and 2015, respectively.

Related-Party Transactions	12 Months Ended
Related-Party Transactions	Dec. 31, 2017
Related Party Transactions [Abstract]
Related-Party Transactions	5. Related-Party Transactions Due from related parties consists of receivables due from another subsidiary of the Parent related to payroll services provided by the Company to the other subsidiary. Due to related parties consists of cash advances, license fees, amounts owed under the intercompany management agreement, and interest charged on outstanding amounts. Amounts due to the Parent that are included in due to related parties on the balance sheet bear interest at a rate of the European Interbank Offered Rate for 12 months (EURIBOR 12) plus 5% per annum. The Company has a management agreement with the Parent, in which the Company pays the Parent a monthly fee for certain services provided by the Parent, which include general sales and administration functions, accounting functions, research and development, legal advice, human resources, and information technology. The Company recorded expenses associated with the management agreement of $1,968 thousand, $3,150 thousand and $1,884 thousand for the year ended December 31, 2017, 2016 and 2015, respectively. For the year ended December 31, 2017, 2016 and 2015, the Company classified $1,811 thousand, $2,969 thousand and $1,704 thousand, respectively, as a component of sales, general and administrative expenses, while $157 thousand, $181 thousand and $180 thousand, respectively, were classified as a component of R&D expenses. As of December 31, 2017, the Company had short-term Parent obligations of $1.4 million consisting of amounts owed under the intercompany management agreement for services provided by Cellectis and costs incurred by Cellectis on behalf of the Company. In consideration of, and as an inducement to, landlord’s agreement to enter into the Lease Agreement, defined in Note 11 Commitments and Contingencies, Cellectis entered into a Lease Guaranty with the landlord, whereby Cellectis has guaranteed all of the Company’s obligations under the Lease Agreement. Cellectis’ guarantee of the Company’s obligations under the sale-leaseback transaction will terminate at the end of the second consecutive calendar year in which the Company tangible net worth exceeds $300 million, as determined in accordance with generally accepted accounting principles. On November 10, 2017, the Company agreed to indemnify Cellectis for any obligations incurred by Cellectis under the Lease Guaranty. This indemnification agreement will become effective at such time as Cellectis owns 50% or less of the Company’s outstanding common stock. TALEN technology was invented by researchers at the University of Minnesota and Iowa State University and exclusively licensed to Cellectis. The Company obtained from Cellectis an exclusive license to the technology for commercial use in plants. TALEN technology is the primary gene-editing technology used by the Company today. The Company will be required to pay a royalty to Cellectis on future sales for the licensing of the technology.

Accrued Liabilities	12 Months Ended
Accrued Liabilities	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Liabilities	6. Accrued Liabilities As of December 31, 2017 and 2016, respectively, the Company had accrued liabilities of $893 thousand and $363 thousand, which consist of non-IPO legal expense, unrecognized income related to construction tax incentive and miscellaneous operating expenses.

Equity Transactions	12 Months Ended
Equity Transactions	Dec. 31, 2017
Equity [Abstract]
Equity Transactions	7. Equity Transactions On August 1, 2015, the Parent made a $40 million capital contribution to the Company in the form of $30 million cash and conversion of a $10 million net payable due to the Parent to equity. On October 1, 2015, the Company entered into an amended and restated contribution agreement with Cellectis and in exchange for the capital contribution, Calyxt issued its parent 17,150,000 shares of Common Stock.

Net Loss per Share	12 Months Ended
Net Loss per Share	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss per Share	8. Net Loss per Share Basic loss per share is computed based on the net loss allocable to common stockholders for each period, divided by the weighted average number of common shares outstanding. All outstanding stock options and restricted stock units are excluded from the calculation since they are anti-dilutive. Due to the existence of net losses for the year ended December 31, 2017, 2016 and 2015, basic and diluted loss per share were the same.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

9. Stock-Based Compensation

Calyxt, Inc. Equity Incentive Plan and Omnibus Plan

The Company adopted the Calyxt, Inc. Equity Incentive Plan, or the Existing Plan, which allows for the grant of stock options to attract and retain highly qualified employees. In June 2017, the Company also adopted an omnibus incentive plan, or the Omnibus Plan, under which the Company granted stock options and restricted stock units to certain of our employees, nonemployees, and certain employees and nonemployees of the Parent.

The options granted under the Existing Plan and the Omnibus Plan were only exercisable upon a triggering event or initial public offering as defined by the plan. Accordingly, with the completion of the IPO on July 25, 2017, the Company recognized compensation expense of $5.6 million for stock options granted under the plans. The stock options issued under the plans had an exercise price equal to the estimated fair value of the stock at the grant date for the Omnibus Plan and the grant date for the Existing Plan.

The following table presents stock-based compensation expense for the years ended December 31, 2017, 2016 and 2015 included in the Company’s statements of operations (in thousands):


	2017		2016		2015
Stock-based compensation expense for:
Employee stock options	$	4,761	$	—	$	—
Employee restricted stock units		1,775		—		—
Nonemployee stock options		4,530		—		—
Nonemployee restricted stock units		654		—		—

	$	11,720	$	—	$	—


	2017		2016		2015
Stock-based compensation expense in operating expense:
Selling, general and administrative	$	5,988	$	—	$	—
Research and development		5,732		—		—

	$	11,720	$	—	$	—

The Company treats stock-based compensation awards granted to employees of the Parent as dividends, which are recorded quarterly. The Company recorded $3.6 million, $0 and $0, respectively, in a deemed dividend to the Parent in the year ended December 31, 2017, 2016 and 2015 for restricted stock units and stock options granted to employees of the Parent.

Equity instruments issued to non-employees include RSUs and options to purchase shares of the Company’s common stock. These RSUs and options vest over a certain period during which services are provided. The Company expenses the fair market value of the awards over the period in which the related services are received. Unvested awards are remeasured to fair value until they vest.

Stock Options

The following table summarizes stock option activity for the year ended December 31, 2017:


	Number of Shares			Weighted- Average Exercise Price Per Share		Aggregate Intrinsic Value (in thousands)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2016		1,930,600		$	4.45				9.1
Granted		2,120,347		$	13.29
Exercised		(68,780	)	$	3.95
Cancelled		(98,735	)	$	1.23

Outstanding at December 31, 2017		3,883,432		$	9.16	$	49,965		8.8

Exercisable at December 31, 2017		1,244,968		$	5.20	$	20,949		8.1

The weighted average grant date fair value for stock options granted during the years ended December 31, 2017, 2016 and 2015 was $2.42, $5.03 and $1.02, respectively. The total fair value of stock options vested during the years ended December 31, 2017, 2016 and 2015 was $6.7 million, $0 and $0, respectively. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2017, 2016 and 2015 was $1.3 million, $0 million and $0 million, respectively. As of December 31, 2017, the total unrecognized stock-based compensation expense related to non-vested stock options is approximately $5.0 million, which is expected to be recognized over a weighted-average period of 4.2 years.

The Company had 1,159,914 stock options that vested upon the completion of the IPO. The stock-based compensation expense related to these awards was $5.6 million, which was recorded upon the completion of the IPO.

In December 2017, stock options held by an employee were modified in connection with the employee’s termination to provide for continued vesting of tranches through the end of 2018. Stock options to purchase an aggregate of 51,622 shares of common stock were modified, and the Company recognized stock-based compensation expense of $0.7 million related to this modification.

The fair value of each stock option is estimated using the Black-Scholes option pricing model at each measurement date. The fair value of stock options under the Black-Scholes model requires management to make assumptions regarding projected employee stock option exercise behaviors, risk-free interest rates, volatility of the stock price, and expected dividends. The awards currently outstanding were granted with vesting terms between two and six years. Certain awards contained a 25% acceleration vesting clause upon a triggering event or initial public offering as defined in the Existing Plan and Omnibus Plan and for 100% accelerated vesting in the event of (a) the termination of employment without cause or (b) the resignation of the employee for good reason within twelve months following a triggering event as defined in the Existing Plan and Omnibus Plan.

The Company has not historically paid cash dividends to its stockholders and currently does not anticipate paying any cash dividends in the foreseeable future. As a result, the Company has assumed a dividend yield of 0%. The risk-free interest rate is based upon the rates of U.S. Treasury bills with a term that approximates the expected life of the option. The Company uses the simplified method, or the lattice method when appropriate, to reasonably estimate the expected life of its option awards. Expected volatility is based upon the volatility of comparable public companies.

The following table provides the assumptions used in the Black-Scholes model for the stock option awards for the years ended December 31, 2017, 2016 and 2015:


	2017		2016		2015
Expected dividend yield		0%		0%		0%
Risk-free interest rate		1.25% - 2.39%		0.64%		1.65%
Expected volatility		27.4% - 45.1%		30%		54.3%
Expected life (in years)		1.22 - 10.00		5.75 - 6.25		5.53

Restricted Stock Units

The following table summarizes the activity of restricted stock units for the year ended December 31, 2017:


	Number of Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value
Unvested balance at December 31, 2016
Granted		1,452,333		$	8.00
Vested		(39,200	)
Cancelled		(39,200	)

Unvested balance at December 31, 2017		1,373,933		$	8.00

The weighted average grant date fair value for RSUs granted during the year ended December 31, 2017 was $8.00. No RSUs were granted during the years ended December 31, 2016 or 2015. The total fair value of RSUs vested during the year ended December 31, 2017 was $314 thousand. As of December 31, 2017, the Company had approximately $7.0 million of unrecognized stock-based compensation expense related to restricted stock units that is expected to be recognized over a weighted-average period of 4.9 years.

Parent Equity Incentive Plan

The weighted average grant date fair value for stock options granted during the years ended December 31, 2017, 2016 and 2015 was $17.16, $0 and $16.45, respectively. The total fair value of stock options vested during the years ended December 31, 2017, 2016 and 2015 was $401 thousand, $900 thousand and $678 thousand, respectively. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2017, 2016 and 2015 was $0 million, $0 million and $0 million, respectively.

The Company’s Parent granted stock options to employees of the Company. Compensation costs related to the grant of the Parent company awards to the Company’s employees has been recognized in the statements of operations with a corresponding credit to stockholders’ equity, representing the Parent’s capital contribution to the Company. The fair value of each stock option is estimated at the grant date using the Black-Scholes option pricing model. The fair value of stock options under the Black-Scholes model requires management to make assumptions regarding projected employee stock option exercise behaviors, risk-free interest rates, volatility of the Company’s stock price, and expected dividends.

The following table provides the range of assumptions used in the Black-Scholes model for the Parent awards for years ended December 31, 2017, 2016 and 2015:


	2017		2016		2015
Expected dividend yield		0%		0%		0%
Risk-free interest rate		0.03% - 0.94%		0.16% - 0.94%		0.16% - 0.94%
Expected volatility		59.09% - 65.64%		59.09% - 60.49%		59.09% - 60.49%
Expected life (in years)		6.00 - 6.12		6.00 - 6.11		6.00 - 6.11

In 2015 the Company’s Parent granted to certain consultants of the Company warrants to purchase Cellectis stock in exchange for services provided to the Company. The Company recorded the fair value of the warrants as a dividend paid to the Parent in exchange for the warrants issued to consultants.

The Company recognized stock-based compensation expense related to its Parent’s grants of stock options and warrants to the Company employees and consultants of $371 thousand, $948 thousand and $692 thousand for the year ended December 31, 2017, 2016 and 2015, respectively. The following table summarizes the stock-based compensation expense for Parent awards (in thousands), which was recognized in the Company’s statements of operations:


	2017		2016		2015
Stock-based compensation expense in operating expenses:
Selling, general and administrative	$	17	$	20	$	16
Research and development		354		928		676

	$371		$948		$692

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

Deferred income tax assets and liabilities are recognized for the differences between the financial statement and income tax reporting basis of assets and liabilities based on currently enacted rates and laws.

A reconciliation of statutory tax expense to actual tax expense is as follows:


	Year Ended December 31,
	Year Ended December 31,
(Amounts in Thousands)	2017			2016			2015
(Amounts in Thousands)	2017			2016			2015
Federal benefit at statutory rate of 34%	($	8,833	)	($	4,109	)	($	2,002	)
State Taxes (Net of Fed. Benefit)		3			—			—
Nondeductible expenses		(154	)		325			237
Recognized R&D tax credits		—			(418	)		—
Other credits generated		—			(58	)		—
Deferred rate change		3,346			—			—
Change in valuation allowance		5,638			4,260			1,765

Total income tax	$	—		$	—		$	—

The total valuation allowance increased by $5.6 million, $4.3 million and 1.8 million for 2017, 2016 and 2015, respectively.

Deferred assets consist of the following:


	Year Ended December 31,
(Amounts in Thousands)	2017			2016
(Amounts in Thousands)	2017			2016
Net operating loss		9,252			8,974
Stock-based compensation		2,691			—
Financing lease obligation		2,131			—
Credits		735			592
Accrued expenses		576			574
Other		8			81

Total deferred tax assets		15,393			10,221
Property and equipment		(2,600	)		(53	)
Deferred revenue		(1	)		9

Total deferred tax liabilities		(2,601	)		(44	)
Less valuation allowance		(12,792	)		(10,177	)

Total	$	—		$	—

The cumulative net operating loss (NOLs) available to offset future income for federal and state reporting purposes was $41.6 million, $24.7 million and $14.9 million at December 31, 2017, 2016 and 2015, respectively. Federal and state net operating loss and credit carryforwards will begin to expire in 2032. Due to potential ownership changes that may have occurred or would occur in the future, IRC Section 382 may place additional limitations on the Company’s ability to utilize the net operating loss carryforward.

The net deferred tax assets have a valuation allowance to reserve against those deferred tax assets that the Company believes are more likely than not to not be realized. In the event that the Company determines that a valuation allowance is no longer required, any benefits realized from the use of the NOLs and credits acquired will reduce its deferred income tax expense. In assessing the recoverability of the deferred tax assets, management considers whether it is more likely than not that a portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income in the periods in which those temporary differences become deductible. Management considers the scheduled reversals of future deferred tax liabilities, projected future taxable income, and tax planning strategies in making this assessment. As such, the Company has recorded a valuation allowance to offset all of its deferred tax assets due to the uncertainty that enough taxable income will be generated in the taxing jurisdiction to utilize the assets. Therefore, the Company has not reflected any benefit of such deferred tax assets in the accompanying financial statements.

The Company has recognized no material uncertain tax positions as of December 31, 2017. The Company files income tax returns in the U.S federal jurisdiction and various state jurisdictions. With few exceptions, the Company is no longer subject to U.S federal or state and local income tax examinations by tax authorities for years before 2013. It is difficult to predict the final timing and resolution of any particular uncertain tax position. Based on the Company’s assessment of many factors, including past experience and complex judgements about future events, the Company does not currently anticipate significant changes in its uncertain tax positions over the next 12 months.

On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act tax reform legislation. This legislation makes significant change in U.S. tax law including a reduction in the corporate tax rates, changes to net operating loss carryforwards and carrybacks, and a repeal of the corporate alternative minimum tax. The legislation reduced the U.S. corporate tax rate from the current rate of 35% to 21%. As a result of the enacted law, the Company was required to revalue deferred tax assets and liability at the enacted rate, which the Company has concluded provisionally had a net reduction in its net deferred tax assets of $3.4 million. This revaluation didn’t have any income tax expense impact due to the full valuation allowance. The other provisions of the Tax Cuts and Jobs Act did not have a material impact on the 2017 financial statements.

In March 2016, the FASB issued guidance within ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. The amendments in ASU 2016-09 to Topic 718, Compensation—Stock Compensation, require recognition of all excess tax benefits and tax deficiencies through income tax expense or benefit in the income statement. The amendments in this Update are effective for annual periods beginning after December 15, 2016. Effective January 1, 2017, the Company has adopted the ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. As a result of adoption, the Company recognized an $813 thousand tax benefit as a reduction of income tax expense, however, due to full valuation allowance, the net impact is zero.

As of December 31, 2017, there were no material changes to what the Company disclosed regarding tax uncertainties or penalties as of December 31, 2016.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. Commitments and Contingencies

Litigation and Claims

Various legal actions, proceedings, and claims (generally, “matters”) are pending or may be instituted or asserted against the Company. The Company accrues for matters when losses are deemed probable and reasonably estimable. Any resulting adjustments, which could be material, are recorded in the period the adjustments are identified. The Company has not identified any legal matters needing to be recorded or disclosed as of December 31, 2017.

Leases

The Company leases the existing office space under an amended non-cancelable operating lease that expires in May 2018. Rent expense is recognized using the straight-line method over the term of the lease. In addition to minimum lease payments, the office lease requires payment of a proportionate share of real estate taxes and building operating expenses. Total rent expense was $270 thousand, $271 thousand and $272 thousand for the year ended December 31, 2017, 2016 and 2015, respectively.

Future minimum lease commitments as of December 31, 2017 are as follows (in thousands):


As of December 31, 2017	Total		1 year		2 years		3 years		4 years		5 years		After 5 years
Financing lease obligations	$	30,042	$	1,054	$	1,336	$	1,336	$	1,336	$	1,336	$	23,644
Operating lease obligations		80		76		1		1		1		1		—

Total contractual obligations	$	30,122	$	1,130	$	1,337	$	1,337	$	1,337	$	1,337	$	23,644

Financing Lease

The Company entered into a sale-lease back transaction (also called the financing lease) on September 6, 2017 with respect to certain real property and improvements located in Roseville, MN, whereby the Company sold the land and other improvements to a third party in exchange for approximately $7 million in cash and the Company committed to an initial lease term of twenty years, with four options to extend the term of the Lease Agreement for five years each. The transaction also included a construction contract for the Company’s new nearly 40,000 square-foot corporate headquarters which when complete will include office, research laboratory space and outdoor growing plots.

During the construction period, the Company will initially pay annual base rent of $490 thousand until the property has been substantially completed, at which time, the lease will commence and the Company will pay annual base rent at the rate of 8% of the total cost which based on the project plan would approximate an annual base rent of $1.4 million. The Lease Agreement is a net lease, whereby the Company is responsible for the other costs and expenses associated with the use of the property. Cellectis entered into a Lease Guaranty with the landlord, whereby Cellectis has guaranteed the Company’s obligations under the Lease Agreement. Cellectis’ guarantee of the Company obligations under the sale-leaseback transaction will terminate at the end of the second consecutive calendar year in which the Company’s tangible net worth exceeds $300 million, as determined in accordance with generally accepted accounting principles. On November 10, 2017, the Company agreed to indemnify Cellectis for any obligations incurred by Cellectis under the Lease Guaranty. The indemnification agreement will become effective at such time as Cellectis owns 50% or less of the Company outstanding common stock.

The Company is responsible for construction cost overruns. As a result of this involvement, the Company is deemed the “owner” for accounting purposes during the construction period and is required to capitalize the construction costs on the balance sheet. The sale of the land and structures also does not qualify for sale-leaseback accounting under ASC 840 as a result of “continuing involvement” and the guarantee of the transaction by Cellectis. Under ASC 840, the “continuing involvement” precludes the Company from derecognizing the assets from the balance sheet. When the assets under construction have been substantially completed the assets associated with the project will be capitalized and depreciated over the term of the lease.

The Company has recorded assets under construction related to the financing lease transaction of $3.1 million and a financing lease obligation of $10.1 million as of December 31, 2017. The Company recognized $0.2 million of interest expense related to this arrangement for the year end December 31, 2017.

Forward Purchase Commitments

The Company has forward purchase commitments with growers to purchase seed and grain at future dates in the amount of approximately $1.6 million that are estimated based on anticipated yield and expected price. This amount is not recorded in the financial statements because the Company has not taken delivery of the seed and grain.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2017
Postemployment Benefits [Abstract]
Employee Benefit Plan	12. Employee Benefit Plan The Company provides a 401(k) defined contribution plan (the Plan) for participation by all regular fulltime employees who have completed three months of service. The Plan provides for a matching contribution equal to 100% of the amount of the employee’s salary deduction up to 3% of the salary per employee and an additional 50% match from 3% to 5% of salary. Employees’ rights to the Company’s matching contributions vest immediately. The Company contributions to the Plan totaled $93 thousand, $66 thousand and $47 thousand for the year ended December 31, 2017, 2016 and 2015, respectively.

Segment and Geographic Information	12 Months Ended
Segment and Geographic Information	Dec. 31, 2017
Segment Reporting [Abstract]
Segment and Geographic Information	13. Segment and Geographic Information The Company has one operating and reportable segment, R&D of plant gene editing. The Company derives substantially all of its revenue from R&D contracts related to plant gene editing located in the US.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events In December 2013, the Company entered into a Research and Commercial License Agreement (the “License Agreement”) with a subsidiary of Bayer Aktiengesellschaft (“Bayer”), pursuant to which we granted Bayer a license to certain patents for the research and commercialization of certain products developed with our TALEN technology. The Company believes that Bayer, which has agreed to acquire Monsanto, Inc. and also to sell a significant portion of its seeds business to BASF SE, has breached the License Agreement by filing patent applications in violation of the License Agreement’s provisions and by failing to make a payment due under the License Agreement. As described elsewhere in this Annual Report, the Company’s commercial success depends, in part, on obtaining and maintaining proprietary rights to intellectual property and defending these rights against third-party challenges. Accordingly, the Company gave notice to Bayer of its termination of the License Agreement, and on March 12, 2018, the Company filed a complaint in Delaware Chancery Court alleging that it properly terminated the License Agreement for Bayer’s material breach. The Company has requested a declaration that the License Agreement has terminated and an order of specific performance requiring Bayer to comply with its post-termination obligations. The Company does not expect to incur any significant losses as a result of the proceedings. However, litigation is inherently uncertain, and there can be no assurances with respect to the outcome or consequences of this litigation.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Use of Estimates

Use of Estimates

Cash and Cash Equivalents

Cash and Cash Equivalents

Trade Accounts Receivable

Trade Accounts Receivable

As of December 31, 2017, the Company had no trade accounts receivables.

Prepaid Expenses and Other Current Assets

Prepaid Expenses and Other Current Assets

Other current assets represent prepayments, R&D tax credits receivable and deposits made by the Company.

Property and Equipment

Property and Equipment


Buildings and other improvements		10–20 years
Leasehold improvements		Remaining lease period
Office furniture and equipment		5–7 years
Computer equipment and software		3–5 years

Leases

Leases

Long-Lived Assets

Long-Lived Assets

There have been no impairment losses recognized for the years ended December 31, 2017, 2016 or 2015.

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Level 1—Financial instruments with unadjusted quoted prices listed on active market exchanges.


	Fair Value Measurements at December 31, 2017 (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	3		—	$	3

Total Assets at Fair Value		—	$	3		—	$	3

Liabilities at Fair Value
Forward purchase contracts		—	$	4		—	$	4

Total Liabilities at Fair Value		—	$	4		—	$	4


	Fair Value Measurements at December 31, 2016, (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	9		—	$	9

Total Assets at Fair Value		—	$	9		—	$	9

Liabilities at Fair Value
Forward purchase contracts		—	$	19		—	$	19

Total Liabilities at Fair Value		—	$	19		—	$	19

Forward Purchase Contracts and Derivatives

Forward Purchase Contracts and Derivatives

The table below summarizes the carrying value of derivative instruments as of December 31, 2017, 2016 and 2015.


	Asset Derivatives					Liability Derivatives
Derivatives not designated as hedging instruments under ASC Topic 815		Fair Value						Fair Value
	Balance Sheet Location	December 31, 2017		December 31, 2016		Balance Sheet Location		December 31, 2017		December 31, 2016
		(expressed in thousands)						(expressed in thousands)
Forward purchase contracts	Prepaid expenses & other current assets	$	3	$	9		Accrued liabilities—current	$	4	$	19

Total derivatives		$	3	$	9			$	4	$	19

Patents

Patents

Revenue Recognition

Revenue Recognition

Cost of Revenue

Cost of Revenue

Research and Development

Research and Development

Stock Based Compensation

Stock Based Compensation

Foreign Currency Transactions

Foreign Currency Transactions

Income Taxes

Income Taxes

Current income taxes are recorded based on statutory obligations for the current operating period for the jurisdictions in which the Company has operations.

Recently Adopted Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Issued Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Estimated Useful Life of Assets Used to Compute Depreciation Using the Straight-line Method

Depreciation expense has been calculated using the following estimated useful lives:


Buildings and other improvements		10–20 years
Leasehold improvements		Remaining lease period
Office furniture and equipment		5–7 years
Computer equipment and software		3–5 years

Summary of Fair Value Measurements


	Fair Value Measurements at December 31, 2017 (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	3		—	$	3

Total Assets at Fair Value		—	$	3		—	$	3

Liabilities at Fair Value
Forward purchase contracts		—	$	4		—	$	4

Total Liabilities at Fair Value		—	$	4		—	$	4


	Fair Value Measurements at December 31, 2016, (expressed in thousands)
	Level 1		Level 2		Level 3		Net Balance
Asset at Fair Value:
Forward purchase contracts		—	$	9		—	$	9

Total Assets at Fair Value		—	$	9		—	$	9

Liabilities at Fair Value
Forward purchase contracts		—	$	19		—	$	19

Total Liabilities at Fair Value		—	$	19		—	$	19

Schedule of Amounts of Non-hedging Derivative Financial Instruments

The table below summarizes the carrying value of derivative instruments as of December 31, 2017, 2016 and 2015.


	Asset Derivatives					Liability Derivatives
Derivatives not designated as hedging instruments under ASC Topic 815		Fair Value						Fair Value
	Balance Sheet Location	December 31, 2017		December 31, 2016		Balance Sheet Location		December 31, 2017		December 31, 2016
		(expressed in thousands)						(expressed in thousands)
Forward purchase contracts	Prepaid expenses & other current assets	$	3	$	9		Accrued liabilities—current	$	4	$	19

Total derivatives		$	3	$	9			$	4	$	19

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Components of Property and Equipment

Property and equipment for the years ended December 31, 2017 and 2016 consists of the following:


(Amounts in thousands)	2017			2016
Land	$	5,690		$	5,690
Buildings and other improvements		4,414			4,304
Leasehold improvements		169			169
Office furniture and equipment		1,672			1,506
Computer equipment and software		20			20
Assets under construction		3,671			37

		15,636			11,726
Less accumulated depreciation		(1,283	)		(732	)

Property and equipment, net	$	14,353		$	10,994

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Stock-based Compensation Expense

The following table presents stock-based compensation expense for the years ended December 31, 2017, 2016 and 2015 included in the Company’s statements of operations (in thousands):


	2017		2016		2015
Stock-based compensation expense for:
Employee stock options	$	4,761	$	—	$	—
Employee restricted stock units		1,775		—		—
Nonemployee stock options		4,530		—		—
Nonemployee restricted stock units		654		—		—

	$	11,720	$	—	$	—


	2017		2016		2015
Stock-based compensation expense in operating expense:
Selling, general and administrative	$	5,988	$	—	$	—
Research and development		5,732		—		—

	$	11,720	$	—	$	—

Summary of Stock Option Activity

The following table summarizes stock option activity for the year ended December 31, 2017:


	Number of Shares			Weighted- Average Exercise Price Per Share		Aggregate Intrinsic Value (in thousands)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2016		1,930,600		$	4.45				9.1
Granted		2,120,347		$	13.29
Exercised		(68,780	)	$	3.95
Cancelled		(98,735	)	$	1.23

Outstanding at December 31, 2017		3,883,432		$	9.16	$	49,965		8.8

Exercisable at December 31, 2017		1,244,968		$	5.20	$	20,949		8.1

Summary of Assumptions used in Black-Scholes Model

The following table provides the assumptions used in the Black-Scholes model for the stock option awards for the years ended December 31, 2017, 2016 and 2015:


	2017		2016		2015
Expected dividend yield		0%		0%		0%
Risk-free interest rate		1.25% - 2.39%		0.64%		1.65%
Expected volatility		27.4% - 45.1%		30%		54.3%
Expected life (in years)		1.22 - 10.00		5.75 - 6.25		5.53

Summary of Activity of Restricted Stock Units

The following table summarizes the activity of restricted stock units for the year ended December 31, 2017:


	Number of Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value
Unvested balance at December 31, 2016
Granted		1,452,333		$	8.00
Vested		(39,200	)
Cancelled		(39,200	)

Unvested balance at December 31, 2017		1,373,933		$	8.00

Cellectis (Parent) [Member]

Summary of Stock-based Compensation Expense

The following table summarizes the stock-based compensation expense for Parent awards (in thousands), which was recognized in the Company’s statements of operations:


	2017		2016		2015
Stock-based compensation expense in operating expenses:
Selling, general and administrative	$	17	$	20	$	16
Research and development		354		928		676

	$371		$948		$692

Summary of Assumptions used in Black-Scholes Model

The following table provides the range of assumptions used in the Black-Scholes model for the Parent awards for years ended December 31, 2017, 2016 and 2015:


	2017		2016		2015
Expected dividend yield		0%		0%		0%
Risk-free interest rate		0.03% - 0.94%		0.16% - 0.94%		0.16% - 0.94%
Expected volatility		59.09% - 65.64%		59.09% - 60.49%		59.09% - 60.49%
Expected life (in years)		6.00 - 6.12		6.00 - 6.11		6.00 - 6.11

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Summary of Reconciliation of Statutory Tax Expense to Actual Tax Expense

A reconciliation of statutory tax expense to actual tax expense is as follows:


	Year Ended December 31,
	Year Ended December 31,
(Amounts in Thousands)	2017			2016			2015
(Amounts in Thousands)	2017			2016			2015
Federal benefit at statutory rate of 34%	($	8,833	)	($	4,109	)	($	2,002	)
State Taxes (Net of Fed. Benefit)		3			—			—
Nondeductible expenses		(154	)		325			237
Recognized R&D tax credits		—			(418	)		—
Other credits generated		—			(58	)		—
Deferred rate change		3,346			—			—
Change in valuation allowance		5,638			4,260			1,765

Total income tax	$	—		$	—		$	—

Schedule of Deferred Assets

Deferred assets consist of the following:


	Year Ended December 31,
(Amounts in Thousands)	2017			2016
(Amounts in Thousands)	2017			2016
Net operating loss		9,252			8,974
Stock-based compensation		2,691			—
Financing lease obligation		2,131			—
Credits		735			592
Accrued expenses		576			574
Other		8			81

Total deferred tax assets		15,393			10,221
Property and equipment		(2,600	)		(53	)
Deferred revenue		(1	)		9

Total deferred tax liabilities		(2,601	)		(44	)
Less valuation allowance		(12,792	)		(10,177	)

Total	$	—		$	—

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Commitments

Future minimum lease commitments as of December 31, 2017 are as follows (in thousands):


As of December 31, 2017	Total		1 year		2 years		3 years		4 years		5 years		After 5 years
Financing lease obligations	$	30,042	$	1,054	$	1,336	$	1,336	$	1,336	$	1,336	$	23,644
Operating lease obligations		80		76		1		1		1		1		—

Total contractual obligations	$	30,122	$	1,130	$	1,337	$	1,337	$	1,337	$	1,337	$	23,644

Nature of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 25, 2017 USD ($) $ / shares shares	Jun. 14, 2017 shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 $ / shares shares
Nature of Business [Line Items]
Place of incorporation			Delaware
Net proceeds from issuance of common stock upon IPO and exercise of overallotment \| $	$ 58,000
Underwriting discounts and commissions \| $	3,100
Offering expenses \| $	$ 3,300
Net proceeds from issuance of common stock upon IPO and exercise of overallotment \| $			$ 57,980
Stock split, conversion ratio	2.45	100
Common stock, shares authorized \| shares	275,000,000	30,000,000	275,000,000	275,000,000
Authorized capital stock \| shares	325,000,000
Common stock, par value \| $ / shares	$ 0.0001		$ 0.0001	$ 0.0001
Preferred stock, shares authorized \| shares	50,000,000		50,000,000	50,000,000
Preferred stock, par value \| $ / shares	$ 0.0001		$ 0.0001	$ 0.0001
Cellectis (Parent) [Member]
Nature of Business [Line Items]
Percentage of ownership in outstanding common stock			79.70%
Common stock, issued and sold \| shares	2,500,000
Net proceeds from issuance of common stock upon IPO and exercise of overallotment \| $	$ 20,000
Outstanding obligation paid to parent \| $	$ 5,700
IPO [Member]
Nature of Business [Line Items]
Common stock, issued and sold \| shares	8,050,000
Common stock issued price per share \| $ / shares	$ 8.00
Underwriters Option to Purchase Additional Shares [Member]
Nature of Business [Line Items]
Common stock, issued and sold \| shares	1,050,000

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Trade accounts receivable	$ 0	$ 110,000
Impairment of long-lived assets	0	0	$ 0
Fair value movements between Level 2 and Level 3	0	0	0
Research and development expense	11,556,000	5,638,000	2,766,000
Income tax expense (benefit)	0	0	0
Accounting Standards Update 2016-09 [Member]
Significant Accounting Policies [Line Items]
Income tax expense (benefit)	(813,000)
Net impact of adoption	0
Level 3 [Member]
Significant Accounting Policies [Line Items]
Financial instruments classified as Level 3	0	0	0
Related-party In-licensing [Member]
Significant Accounting Policies [Line Items]
Research and development expense	93,000	44,000	86,000
Third-party In-licensing [Member]
Significant Accounting Policies [Line Items]
Research and development expense	$ 447,000	$ 539,000	$ 165,000

Summary of Significant Accounting Policies - Schedule of Estimated Useful Life of Assets Used to Compute Depreciation Using the Straight-Line Method (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings and Other Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	10 years
Buildings and Other Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	20 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	Remaining lease period
Office Furniture and Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Office Furniture and Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	7 years
Computer Equipment and Software [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Computer Equipment and Software [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years

Summary of Significant Accounting Policies - Summary of Fair Value Measurements (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Asset at Fair Value:
Total Assets at Fair Value	$ 3	$ 9
Liabilities at Fair Value
Total Liabilities at Fair Value	4	19
Forward Purchase Contracts [Member]
Asset at Fair Value:
Forward purchase contracts	3	9
Liabilities at Fair Value
Forward purchase contracts	4	19
Level 2 [Member]
Asset at Fair Value:
Total Assets at Fair Value	3	9
Liabilities at Fair Value
Total Liabilities at Fair Value	4	19
Level 2 [Member] \| Forward Purchase Contracts [Member]
Asset at Fair Value:
Forward purchase contracts	3	9
Liabilities at Fair Value
Forward purchase contracts	$ 4	$ 19

Summary of Significant Accounting Policies - Schedule of Amounts of Non-hedging Derivative Financial Instruments (Detail) - Derivatives Not Designated as Hedging Instruments [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 3	$ 9
Liability Derivatives	4	19
Forward Purchase Contracts [Member] \| Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	3	9
Forward Purchase Contracts [Member] \| Accrued Liabilities Current [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 4	$ 19

Concentrations of Credit Risk - Additional Information (Detail) $ in Thousands			12 Months Ended
	Dec. 31, 2016 USD ($) Customer	Dec. 31, 2015 Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016 USD ($) Customer	Dec. 31, 2015 Customer
Concentration Risk [Line Items]
Trade accounts receivable \| $	$ 110		$ 0	$ 110
Trade Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, number of customers	1	2
Revenue Concentration [Member]
Concentration Risk [Line Items]
Concentration risk, number of customers			3	4	3
Customer 1 [Member] \| Trade Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	50.00%
Customer 1 [Member] \| Revenue Concentration [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			51.00%	33.00%	38.00%
Customer 2 [Member] \| Trade Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		50.00%
Customer 2 [Member] \| Revenue Concentration [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			40.60%	28.00%	26.00%
Customer 3 [Member] \| Revenue Concentration [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			6.70%	19.00%	20.00%
Customer 4 [Member] \| Revenue Concentration [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage				16.00%

Property and Equipment - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 15,636	$ 11,726
Less accumulated depreciation	(1,283)	(732)
Property and equipment, net	14,353	10,994
Land [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	5,690	5,690
Buildings and Other Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	4,414	4,304
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	169	169
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	1,672	1,506
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	20	20
Asset Under Construction [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 3,671	$ 37

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 15,636	$ 11,726
Depreciation expense	551	345	$ 147
Asset Under Construction [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 3,671	$ 37

Related-Party Transactions - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Due to related parties	$ 1,350,000	$ 1,712,000
Minimum net worth required	300,000,000
Cellectis (Parent) [Member]
Related Party Transaction [Line Items]
Minimum net worth required	$ 300,000,000
Cellectis (Parent) [Member] \| Maximum [Member]
Related Party Transaction [Line Items]
Threshold percentage of ownership in outstanding common stock to enact indemnification agreement	50.00%
EURIBOR 12 [Member] \| Cellectis (Parent) [Member]
Related Party Transaction [Line Items]
Debt instrument, basis spread on variable rate	5.00%
Management Agreement [Member] \| Cellectis (Parent) [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 1,968,000	3,150,000	$ 1,884,000
Due to related parties	1,400,000
Selling, General and Administrative [Member] \| Management Agreement [Member] \| Cellectis (Parent) [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1,811,000	2,969,000	1,704,000
Research and Development [Member] \| Management Agreement [Member] \| Cellectis (Parent) [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 157,000	$ 181,000	$ 180,000

Accrued Liabilities - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued liabilities	$ 893	$ 363

Equity Transactions - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Oct. 01, 2015	Aug. 01, 2015	Dec. 31, 2015
Stockholders Equity Disclosure [Line Items]
Parent capital contribution			$ 40,000
Parent capital contribution, cash			$ 30,000
Cellectis (Parent) [Member]
Stockholders Equity Disclosure [Line Items]
Parent capital contribution		$ 40,000
Parent capital contribution, cash		30,000
Parent capital contribution, conversion of net payable to equity		$ 10,000
Parent capital contribution, shares issued	17,150,000

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends			$ 110
Omnibus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 11,720
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 5,600
IPO [Member] \| Omnibus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Completion date of initial public offering	July 25, 2017
Compensation expense	$ 5,600
Nonemployee Restricted Stock Units [Member] \| Omnibus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	654
Cellectis (Parent) [Member] \| Nonemployee Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends	$ 3,600	$ 0	$ 0

Stock-Based Compensation - Summary of Stock-based Compensation Expense (Detail) - Omnibus Plan [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 11,720
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	5,988
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	5,732
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	4,761
Employee Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,775
Nonemployee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	4,530
Nonemployee Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 654

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of shares, Outstanding, Beginning Balance	1,930,600
Number of shares, Granted	2,120,347
Number of shares, Exercised	(68,780)
Number of shares, Canceled	(98,735)
Number of shares, Outstanding, Ending Balance	3,883,432	1,930,600
Number of shares, Exercisable at September 30, 2017	1,244,968
Weighted average exercise price per share, Granted	$ 13.29
Weighted average exercise price per share, Exercised	3.95
Weighted average exercise price per share, Canceled	1.23
Weighted average exercise price per share outstanding	9.16	$ 4.45
Weighted average exercise price per share Exercisable	$ 5.20
Aggregate intrinsic value, Outstanding	$ 49,965
Aggregate intrinsic value, Exercisable	$ 20,949
Weighted average remaining contractual life, Outstanding	8 years 9 months 18 days	9 years 1 month 6 days
Weighted average remaining contractual life, Exercisable	8 years 1 month 6 days

Stock-Based Compensation - Stock Options - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value for stock options granted		$ 2.42	$ 5.03	$ 1.02
Total fair value of stock options vested		$ 6.7	$ 0.0	$ 0.0
Aggregate intrinsic value of stock options exercised		1.3	$ 0.0	$ 0.0
Total unrecognized stock-based compensation expense related to non-vested stock options	$ 5.0	$ 5.0
Unrecognized stock-based compensation expense related to non-vested stock options period of recognition		4 years 2 months 12 days
Dividend yield percentage		0.00%	0.00%	0.00%
Employee Termination [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 0.7
Stock-based compensation purchase	51,622
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock options vested		1,159,914
Compensation expense		$ 5.6
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period		2 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, vesting period		6 years
Acceleration Vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting		25.00%
Acceleration Vesting [Member] \| Employee Termination [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting		100.00%

Stock-Based Compensation - Summary of Assumptions used in Black-Scholes Model (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.25%	0.64%	1.65%
Risk-free interest rate, maximum	2.39%
Expected volatility, minimum	27.40%	30.00%	54.30%
Expected volatility, maximum	45.10%
Expected life (in years)			5 years 6 months 10 days
Cellectis (Parent) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	0.03%	0.16%	0.16%
Risk-free interest rate, maximum	0.94%	0.94%	0.94%
Expected volatility, minimum	59.09%	59.09%	59.09%
Expected volatility, maximum	65.64%	60.49%	60.49%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	1 year 2 months 19 days	5 years 9 months
Minimum [Member] \| Cellectis (Parent) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years	6 years	6 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	10 years	6 years 2 months 30 days
Maximum [Member] \| Cellectis (Parent) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years 1 month 13 days	6 years 1 month 9 days	6 years 1 month 9 days

Stock-Based Compensation - Summary of Activity of Restricted Stock Units (Detail) - Restricted Stock Units [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units outstanding, Unvested beginning balance	0
Number of restricted stock units outstanding, Granted	1,452,333	0	0
Number of restricted stock units outstanding, Vested	(39,200)
Number of restricted stock units outstanding, Cancelled	(39,200)
Number of restricted stock units outstanding, Unvested ending balance	1,373,933	0
Weighted-average grant date fair value, Unvested beginning balance	$ 0
Weighted-average grant date fair value, Granted	8.00
Weighted-average grant date fair value, Vested	0
Weighted-average grant date fair value, Cancelled	0
Weighted-average grant date fair value, Unvested ending balance	$ 8.00	$ 0

Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense, expected recognition weighted-average period	4 years 2 months 12 days
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value, Granted	$ 8.00
Number of restricted stock units granted	1,452,333	0	0
Total fair value vested	$ 314
Unrecognized stock-based compensation expense related to restricted stock units	$ 7,000
Unrecognized stock-based compensation expense, expected recognition weighted-average period	4 years 10 months 24 days

Stock-Based Compensation - Parent Equity Incentive Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value for stock options granted	$ 2.42	$ 5.03	$ 1.02
Total fair value of stock options vested	$ 6,700	$ 0	$ 0
Aggregate intrinsic value of stock options exercised	$ 1,300	$ 0	$ 0
Equity Incentive Plan [Member] \| Cellectis (Parent) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value for stock options granted	$ 17.16	$ 0.00	$ 16.45
Total fair value of stock options vested	$ 401	$ 900	$ 678
Aggregate intrinsic value of stock options exercised	0	0	0
Stock-based compensation expense	371	948	692
Equity Incentive Plan [Member] \| Cellectis (Parent) [Member] \| Stock Options and Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 371	$ 948	$ 692

Stock-Based Compensation - Summary of Stock-based Compensation Expense, Recognized in Statements of Operations (Detail) - Cellectis (Parent) [Member] - Equity Incentive Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 371	$ 948	$ 692
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	17	20	16
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 354	$ 928	$ 676

Income Taxes - Summary of Reconciliation of Statutory Tax Expense to Actual Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal benefit at statutory rate of 34%	$ (8,833)	$ (4,109)	$ (2,002)
State Taxes (Net of Fed. Benefit)	3
Nondeductible expenses	(154)	325	237
Recognized R&D tax credits		(418)
Other credits generated		(58)
Deferred rate change	3,346
Change in valuation allowance	5,638	4,260	1,765
Total income tax	$ 0	$ 0	$ 0

Income Taxes - Summary of Reconciliation of Statutory Tax Expense to Actual Tax Expense (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory rate	34.00%	34.00%	34.00%

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Change in valuation allowance	$ 5,638,000	$ 4,260,000	$ 1,765,000
Cumulative net operating loss	$ 41,600,000	$ 24,700,000	$ 14,900,000
Net operating loss expiration beginning period	2032
U.S. corporate tax rate	34.00%	34.00%	34.00%
Net reduction in net deferred tax assets	$ 3,346,000
Income tax expense (benefit)	$ 0	$ 0	$ 0
Scenario, Plan [Member]
Income Taxes [Line Items]
U.S. corporate tax rate	21.00%
Accounting Standards Update 2016-09 [Member]
Income Taxes [Line Items]
Income tax expense (benefit)	$ (813,000)
Net impact of adoption	$ 0

Income Taxes - Schedule of Deferred Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets and Liabilities [Abstract]
Net operating loss	$ 9,252	$ 8,974
Stock-based compensation	2,691
Financing lease obligation	2,131
Credits	735	592
Accrued Expenses	576	574
Other	8	81
Total deferred tax assets	15,393	10,221
Property and equipment	(2,600)	(53)
Deferred Revenue	(1)	9
Total deferred tax liabilities	(2,601)	(44)
Less valuation allowance	(12,792)	(10,177)
Total	$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail)		12 Months Ended
	Sep. 06, 2017 USD ($) ft² Options	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Other Commitments [Line Items]
Operating lease expiration date		2018-05
Total rent expense under operating lease		$ 270,000	$ 271,000	$ 272,000
Sale-leaseback transaction date		Sep. 06, 2017
Cash received upon sale of land and other improvements to third party	$ 7,000,000	$ 6,957,000
Lease term	20 years
Number of lease extension options \| Options	4
Extension term of lease agreement	5 years
Annual base rent expense		490,000
Annual base rent		$ 1,400,000
Percentage of annual base rent		8.00%
Minimum net worth required		$ 300,000,000
Gross property and equipment		15,636,000	$ 11,726,000
Financing lease obligation		10,148,000
Interest expense related to finance lease		200,000
Forward purchase commitment amount		1,600,000
Corporate Headquarters [Member]
Other Commitments [Line Items]
Office and lab building area \| ft²	40,000
Assets Under Construction Held Under Finance Lease [Member]
Other Commitments [Line Items]
Gross property and equipment		3,100,000
Cellectis (Parent) [Member]
Other Commitments [Line Items]
Minimum net worth required		$ 300,000,000
Cellectis (Parent) [Member] \| Maximum [Member]
Other Commitments [Line Items]
Threshold percentage of ownership in outstanding common stock to enact indemnification agreement		50.00%

Commitments and Contingencies - Summary of Future Minimum Lease Commitments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Contractual Obligation, Fiscal Year Maturity Schedule [Abstract]
Financing lease obligations, Total	$ 30,042
Financing lease obligations, 1 year	1,054
Financing lease obligations, 2 years	1,336
Financing lease obligations, 3 years	1,336
Financing lease obligations, 4 years	1,336
Financing lease obligations, 5 years	1,336
Financing lease obligations, After 5 years	23,644
Operating lease obligations, Total	80
Operating lease obligations, 1 year	76
Operating lease obligations, 2 years	1
Operating lease obligations, 3 years	1
Operating lease obligations, 4 years	1
Operating lease obligations, 5 years	1
Operating lease obligations, After 5 years	0
Total contractual obligations	30,122
Total contractual obligations, 1 year	1,130
Total contractual obligations, 2 years	1,337
Total contractual obligations, 3 years	1,337
Total contractual obligations, 4 years	1,337
Total contractual obligations, 5 years	1,337
Total contractual obligations, After 5 years	$ 23,644

Employee Benefit Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan description	The Company provides a 401(k) defined contribution plan (the Plan) for participation by all regular fulltime employees who have completed three months of service
Percentage of matching contribution to plan	100.00%
Percentage of salary for matching contribution per employee	3.00%
Percentage of additional matching contribution to plan	50.00%
Contributions to the plan by employer	$ 93	$ 66	$ 47
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percentage of salary for additional matching contribution per employee	3.00%
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percentage of salary for additional matching contribution per employee	5.00%

Segment and Geographic Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 Segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1