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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Oct. 31, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	ARVN
Entity Registrant Name	ARVINAS, INC.
Entity Central Index Key	0001655759
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-38672
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-2566120
Entity Address, Address Line One	5 Science Park
Entity Address, Address Line Two	395 Winchester Ave
Entity Address, City or Town	New Haven
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06511
City Area Code	203
Local Phone Number	535-1456
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		33,748,982

Condensed Consolidated Balance Sheets (unaudited) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 12,135,475	$ 3,190,056
Marketable securities	178,375,159	184,637,640
Account receivable	59,330	2,775,831
Other receivables	5,142,227	2,255,966
Prepaid expenses and other current assets	3,951,152	2,818,286
Total current assets	199,663,343	195,677,779
Property, equipment and leasehold improvements, net	7,152,151	3,583,036
Operating lease right of use assets	2,257,544
Other assets	20,760	20,760
Total assets	209,093,798	199,281,575
Current liabilities:
Accounts payable	2,277,824	2,758,184
Accrued expenses	6,226,971	4,001,276
Deferred revenue	20,294,456	16,065,957
Current portion of long-term debt		154,461
Current portion of operating lease liability	597,014
Total current liabilities	29,396,265	22,979,878
Deferred revenue	41,770,160	37,484,714
Long term debt, net of current portion	2,000,000	2,000,000
Operating lease liability	1,767,775
Other noncurrent liability		150,000
Total liabilities	74,934,200	62,614,592
Commitments and Contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 33,076,557 and 31,235,458 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	33,076	31,236
Accumulated deficit	(351,509,130)	(302,264,619)
Additional paid-in capital	485,439,007	439,118,089
Accumulated other comprehensive income (loss)	196,645	(217,723)
Total stockholders’ equity	134,159,598	136,666,983
Total liabilities and stockholders’ equity	$ 209,093,798	$ 199,281,575

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Common Stock Par Or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock Shares Issued	33,076,557	31,235,458
Common Stock Shares Outstanding	33,076,557	31,235,458

Condensed Consolidated Statements of Operations (unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 30,050,227	$ 3,375,264	$ 38,083,205	$ 10,883,755
Operating expenses:
Research and development	16,588,050	13,149,879	46,779,047	30,631,531
General and administrative	7,957,364	4,284,231	20,038,772	7,110,723
Total operating expenses	24,545,414	17,434,110	66,817,819	37,742,254
Income (loss) from operations	5,504,813	(14,058,846)	(28,734,614)	(26,858,499)
Other income (expenses)
Other income, net	405,302	160,100	840,153	418,494
Change in fair value of preferred unit warrant	0	0	0	(193,779)
Interest income	1,112,415	523,338	3,394,269	1,273,988
Interest expense	(22,903)	(12,264)	(69,319)	(32,804)
Total other income	1,494,814	671,174	4,165,103	1,465,899
Loss from equity method investment	(24,675,000)	0	(24,675,000)	0
Net loss	(17,675,373)	(13,387,672)	(49,244,511)	(25,392,600)
Change in fair value of redeemable convertible preferred units	0	(112,050,609)	0	(198,366,756)
Net loss attributable to common shares	$ (17,675,373)	$ (125,438,281)	$ (49,244,511)	$ (223,759,356)
Net loss per common share, basic and diluted	$ (0.54)	$ (62.38)	$ (1.54)	$ (115.62)
Weighted average common shares outstanding, basic and diluted	32,740,486	2,010,807	31,876,074	1,935,299

Condensed Consolidated Statements of Comprehensive Loss (unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (17,675,373)	$ (13,387,672)	$ (49,244,511)	$ (25,392,600)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	(103,505)	49,391	414,368	(37,472)
Comprehensive loss	$ (17,778,878)	$ (13,338,281)	$ (48,830,143)	$ (25,430,072)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Redeemable Convertible Preferred Units/Shares and Changes in Members'/Stockholders' Equity (unaudited) - USD ($)	Total	Accumulated Deficit	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Series A Redeemable Convertible Preferred Units	Series B Redeemable Convertible Preferred Units	Series C Redeemable Convertible Preferred Units	Series A,B and C Convertible Preferred Shares	Common Units Member Units	Common Shares	Incentive Units Member Units
Balance at Dec. 31, 2017					$ 19,768,025	$ 41,712,407
Balance, Units/Shares at Dec. 31, 2017					22,463,665	24,977,489
Balance at Dec. 31, 2017	$ (61,234,562)	$ (62,417,397)		$ (9,751)					$ 6,167		$ 1,186,419
Balance, Units at Dec. 31, 2017									1,897,544		11,927,381
Incentive unit-based compensation	6,189,011										$ 6,189,011
Incentive unit-based compensation, Units/Shares											5,424,605
Exercise of Series A redeemable convertible preferred warrant					$ 319,667
Exercise of Series A redeemable convertible preferred warrant, Units					110,116
Issuance of Series C redeemable convertible preferred units							$ 55,000,001
Issuance of Series C redeemable convertible preferred units, Units							16,467,066
Change in redemption value of redeemable convertible preferred units	(198,366,756)	(198,366,756)			$ 91,044,716	$ 81,253,577	$ 26,068,463
Net loss	(25,392,600)	(25,392,600)
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares					$ (111,132,408)	$ (122,965,984)	$ (81,068,464)	$ 315,166,856
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares, Units/Shares					(22,573,781)	(24,977,489)	(16,467,066)	64,018,336
Conversion of common and incentive units to common and restricted stock			$ 7,377,913						$ (6,167)	$ 3,684	$ (7,375,430)
Conversion of common and incentive units to common and restricted stock, Units/Shares									(1,897,544)	3,683,639	(17,351,986)
Unrealized gain (loss) on available-for-sale securities	(37,472)			(37,472)
Balance at Sep. 30, 2018								$ 315,166,856
Balance, Units/Shares at Sep. 30, 2018								64,018,336
Balance at Sep. 30, 2018	(278,842,379)	(286,176,753)	7,377,913	(47,223)						$ 3,684
Balance, Units at Sep. 30, 2018										3,683,639
Balance at Jun. 30, 2018					$ 65,818,538	$ 79,178,640	$ 57,799,402
Balance, Units/Shares at Jun. 30, 2018					22,463,665	24,977,489	16,467,066
Balance at Jun. 30, 2018	(158,515,897)	(160,738,472)		(96,614)					$ 6,167		$ 2,313,022
Balance, Units at Jun. 30, 2018									1,897,544		17,315,339
Incentive unit-based compensation	5,062,408										$ 5,062,408
Incentive unit-based compensation, Units/Shares											36,647
Exercise of Series A redeemable convertible preferred warrant					$ 319,667
Exercise of Series A redeemable convertible preferred warrant, Units					110,116
Change in redemption value of redeemable convertible preferred units	(112,050,609)	(112,050,609)			$ 44,994,203	$ 43,787,344	$ 23,269,062
Net loss	(13,387,672)	(13,387,672)
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares					$ (111,132,408)	$ (122,965,984)	$ (81,068,464)	$ 315,166,856
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares, Units/Shares					(22,573,781)	(24,977,489)	(16,467,066)	64,018,336
Conversion of common and incentive units to common and restricted stock			7,377,913						$ (6,167)	$ 3,684	$ (7,375,430)
Conversion of common and incentive units to common and restricted stock, Units/Shares									(1,897,544)	3,683,639	(17,351,986)
Unrealized gain (loss) on available-for-sale securities	49,391			49,391
Balance at Sep. 30, 2018								$ 315,166,856
Balance, Units/Shares at Sep. 30, 2018								64,018,336
Balance at Sep. 30, 2018	$ (278,842,379)	(286,176,753)	7,377,913	(47,223)						$ 3,684
Balance, Units at Sep. 30, 2018										3,683,639
Balance, Units/Shares at Oct. 01, 2018	0
Balance at Dec. 31, 2018	$ 136,666,983	(302,264,619)	439,118,089	(217,723)						$ 31,236
Balance, Units at Dec. 31, 2018										31,235,458
Stock-based compensation	15,091,269		15,091,269
Issuance of common stock	29,454,033		29,452,687							$ 1,346
Stock Issued During Period, Shares, New Issues										1,346,313
Net loss	(49,244,511)	(49,244,511)
Restricted stock vesting			(383)							$ 383
Restricted stock vesting, Shares										383,695
Proceeds from exercise of stock options	1,777,456		1,777,345							$ 111
Proceeds from exercise of stock options, Shares										111,091
Unrealized gain (loss) on available-for-sale securities	414,368			414,368
Balance at Sep. 30, 2019	134,159,598	(351,509,130)	485,439,007	196,645						$ 33,076
Balance, Units at Sep. 30, 2019										33,076,557
Balance at Jun. 30, 2019	116,505,261	(333,833,757)	450,007,344	300,150						$ 31,524
Balance, Units at Jun. 30, 2019										31,523,474
Stock-based compensation	4,601,214		4,601,214
Issuance of common stock	29,454,033		29,452,687							$ 1,346
Stock Issued During Period, Shares, New Issues										1,346,313
Net loss	(17,675,373)	(17,675,373)
Restricted stock vesting			(120)							$ 120
Restricted stock vesting, Shares										120,647
Proceeds from exercise of stock options	1,377,968		1,377,882							$ 86
Proceeds from exercise of stock options, Shares										86,123
Unrealized gain (loss) on available-for-sale securities	(103,505)			(103,505)
Balance at Sep. 30, 2019	$ 134,159,598	$ (351,509,130)	$ 485,439,007	$ 196,645						$ 33,076
Balance, Units at Sep. 30, 2019										33,076,557

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (49,244,511)	$ (25,392,600)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of debt discount	15,149	13,473
Change in fair value of preferred unit warrant liability	0	193,779
Depreciation and amortization	1,024,845	483,052
Net accretion of bond discounts/premiums	(109,870)	213,190
Amortization of right to use assets	506,855	0
Non-cash compensation	15,091,269	6,189,011
Changes in operating assets and liabilities:
Account receivable	2,716,501	25,000,000
Other receivables	(2,886,261)	(1,138,426)
Prepaid expenses and other current assets	(1,282,866)	(2,565,154)
Accounts payable	(618,960)	704,233
Accrued expenses	2,225,695	319,657
Deferred revenue	8,513,945	(7,883,755)
Operating lease liabilities	(399,610)	0
Net cash used in operating activities	(24,447,819)	(3,863,540)
Cash flows from investing activities:
Purchase of marketable securities	(113,056,097)	(114,393,545)
Maturities of marketable securities	119,842,816	38,799,000
Purchase of property, equipment and leasehold improvements	(4,455,360)	(2,209,112)
Net cash provided by (used in) investing activities	2,331,359	(77,803,657)
Cash flows from financing activities:
Repayments of long-term debt	(169,610)	(129,191)
Proceeds from long term debt	0	2,000,000
Proceeds from issuance of common stock	29,454,033	0
Proceeds from sale of redeemable convertible preferred units	0	55,000,001
Proceeds from exercise of redeemable convertible preferred warrant	0	75,000
Proceeds from exercise of stock options	1,777,456	0
Net cash provided by financing activities	31,061,879	56,945,810
Net increase (decrease) in cash and cash equivalents	8,945,419	(24,721,387)
Cash and cash equivalents, beginning of the period	3,190,056	30,912,391
Cash and cash equivalents, end of the period	12,135,475	6,191,004
Supplemental disclosure of cash flow information:
Purchases of property, equipment and leasehold improvements unpaid at period end	138,600	322,301
Deferred offering costs included in accrued expenses	0	663,252
Cash paid for interest	59,586	19,331
Change in fair value of redeemable convertible preferred units	$ 0	$ (198,366,756)

Nature of Business

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Business

1. Nature of Business

Arvinas, Inc. and subsidiaries (the Company) is a clinical-stage biopharmaceutical company dedicated to improving the lives of patients suffering from debilitating and life-threatening diseases through the discovery, development and commercialization of therapies that degrade disease-causing proteins. The Company expects to incur additional operating losses and negative operating cash flows for the foreseeable future.

On October 1, 2018, the Company completed an initial public offering (IPO) in which the Company issued and sold 7,500,000 shares of common stock at a public offering price of $16.00 per share. In October 2018, the underwriters of the IPO exercised an option to purchase 200,482 additional shares of the Company’s common stock at an offering price of $16.00 per share. The Company’s aggregate gross proceeds from the sale of shares in the IPO, including the option, were $123.2 million before underwriting discounts and commissions and expenses of $12.0 million.

On October 1, 2018, all of the outstanding shares of convertible preferred stock automatically converted into 19,697,928 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of preferred stock outstanding.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Unaudited Interim Financial Statements

The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and pursuant to the rules and regulations of the Securities and Exchange Commission. The year-end condensed consolidated balance sheet data was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. These condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the years ended December 31, 2018 and 2017 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission on March 26, 2019 (the Annual Report). The condensed consolidated financial statements, in the opinion of management, reflect all normal and recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations.

Equity Method Investments

The Company accounts for investments for which it does not have a controlling interest in accordance with Accounting Standards Codification (ASC) 323, Investments – Equity Method and Joint Ventures. The Company recognizes its pro-rata share of income and losses in the investment in “Loss from equity method investment” on the consolidated statement of operations and comprehensive loss, with a corresponding change to the investment in equity method investment on the consolidated balance sheet. After recording of losses in the current period, the investment has been reduced to $0.

Recently Adopted Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases. ASU 2016-02 requires lessees to present right-of-use assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. The guidance is effective for years beginning after December 15, 2018 and is to be applied using a modified retrospective approach applied at the beginning of the earliest comparative period in the financial statements or in the year of adoption with a cumulative effect to the opening balance of retained earnings. The Company adopted the new guidance as of January 1, 2019 using the modified retrospective adoption method in which it did not restate prior periods. The Company elected the practical expedient to include both lease and non-lease components as a single component and account for it as a lease. In adopting the standard, the Company also elected to utilize several other practical expedients, including not reassessing contracts for classification as a lease, not having to reassess the lease classification of existing leases, and not reassessing the initial direct costs of existing leases. The adoption of this standard resulted in the recognition of right-of-use assets and related lease liabilities of approximately $2.4 million related to its operating lease commitments on the Condensed Consolidated Balance Sheet as of January 1, 2019.

In June 2018, the FASB issued ASU No. 2018-07, Improvements in Nonemployee Share-Based Payment Accounting. ASU 2018-07 aligns the accounting for share-based payment awards to nonemployees with the accounting for share-based awards to employees. ASU 2018-07 is effective for interim and annual reporting periods beginning after December 15, 2018 and early adoption is permitted. The Company adopted ASU 2018-07 in the first quarter of 2019. The adoption of the standard was immaterial to the accompanying condensed consolidated financial statements.

During the three months ended September 30, 2019, there were no other changes to the Company’s significant accounting policies as described in Note 2 to the financial statements included in the Company’s condensed consolidated financial statements as of December 31, 2018 and 2017 and for the years then ended included in the Annual Report.

Research Collaboration and License Agreements

9 Months Ended

Sep. 30, 2019

Research Collaboration And License Agreements [Abstract]

Research Collaboration and License Agreements

3. Research Collaboration and License Agreements

In December 2017, the Company entered into a Research Collaboration and License Agreement with Pfizer, Inc. (Pfizer) (the Pfizer Collaboration Agreement). Under the terms of the Pfizer Collaboration Agreement, the Company received an upfront non-refundable payment and certain additional payments totaling $28.0 million in 2018 in exchange for use of the Company’s technology license and to fund Pfizer-related research as defined within the agreement. These payments are being recognized as revenue over the total estimated period of performance. The Company is also eligible to receive up to an additional $37.5 million in non-refundable option payments if Pfizer exercises its options for all targets under the agreement. Pfizer exercised an option for $2.5 million in December 2018 and the amount was included in accounts receivable at December 31, 2018. The option will be recognized as revenue over the estimated period of performance. The Company is also entitled to receive up to $225 million in development milestone payments and up to $550 million in sales-based milestone payments for all designated targets under the Pfizer Collaboration Agreement, as well as tiered royalties based on sales.

In September 2015, the Company entered into an Option and License Agreement with Genentech, Inc. and F. Hoffman-La Roche Ltd. (together, Genentech) (the Genentech Agreement). During 2015, the Company received an upfront non-refundable payment of $11.0 million in exchange for use of the Company’s technology license and to fund Genentech-related research as defined within the Genentech Agreement. In November 2017, the Company entered into an Amended and Restated Option, License, and Collaboration Agreement with Genentech, Inc. and F. Hoffman-La Roche Ltd. (the Genentech Modification), amending the Genentech Agreement. Under the Genentech Modification, the Company received additional upfront non-refundable payments of $34.5 million to fund Genentech-related research and Genentech has the right to designate up to ten targets. The Company is eligible to receive up to $27.5 million in additional expansion target payments if Genentech exercises its options on all remaining targets. Upfront non-refundable payments are recognized as revenue over the total estimated period of performance. The Company is eligible to receive up to $44.0 million per target in development milestone payments, $52.5 million in regulatory milestone payments and $60.0 million in commercial milestones based on sales thresholds as well as tiered royalties based on sales.

In June 2019, the Company and Bayer AG entered into a Collaboration and License Agreement (Bayer Collaboration Agreement) setting forth the Company’s collaboration with Bayer AG to identify or optimize proteolysis targeting chimeras, or PROTAC® targeted protein degraders, that mediate for degradation of target proteins (Targets), using the Company’s proprietary platform technology, which Targets will be selected by Bayer AG, subject to certain exclusions and limitations. The Bayer Collaboration Agreement became effective in July 2019. Under the terms of the Bayer Collaboration Agreement, the Company received an upfront non-refundable payment of $17.5 million in exchange for the use of the Company’s technology license. The Company also received a $1.5 million payment to fund research activities and Bayer is committed to funding an additional $10.5 million through 2022. These payments are being recognized over the total estimated period of performance. The Company is also eligible to receive up to $197.5 million in development milestone payments and up to $490.0 million in sales-based milestone payments for all designated Targets. In addition, the Company is eligible to receive, on net sales of PROTAC targeted protein degrader-related products, mid-single digit to low-double digit tiered royalties, which may be subject to reductions.

The Company determined that the Bayer Collaboration Agreement and the Stock Purchase Agreement should be evaluated as a combined contract in accordance with ASC 606, Revenue from Contracts with Customers, given that the agreements were entered into at the same time and have the same commercial objective to provide funding to further the Company’s research utilizing its proprietary technology. The Company identified the elements under the agreements as license and research revenue and the issuance of the common stock. The Company determined the fair value of the shares sold under the Stock Purchase Agreement to be $2.9 million less than the contractual purchase price stipulated in the agreement. In accordance with the applicable accounting guidance in ASC 815-40, Contracts in Entity’s Own Equity, the Company determined that the sale of stock should be recorded at fair value. Therefore, the Company allocated the additional $2.9 million of consideration received under the Stock Purchase Agreement to the Bayer Collaboration Agreement given that the two contracts were determined to be combined contracts. This amount has, therefore, been added to the total transaction price and was included in initial contract liabilities balances.

Information about contract liabilities, which are recorded as deferred revenue on the condensed consolidated balance sheets, is as follows:

	September 30,		December 31,
	2019		2018
Contract liabilities	$	62,064,616	$	53,550,671
Revenues recognized in the period from:
Amounts included in deferred revenue in previous periods	$	12,049,468	$	13,553,136

Changes in deferred revenue from December 31, 2018 to September 30, 2019 were due to additions to deferred revenue of $21.9 million related to the Bayer Collaboration Agreement and $13.4 million of revenue recognized on the research collaboration and license agreements.

The aggregate amount of the transaction price allocated to performance obligations that are unsatisfied as of September 30, 2019 was $62.1 million, which is expected to be recognized as revenue for the years ending December 31 are:

Remainder of 2019	$	6.0
2020		18.9
2021		18.7
2022		13.7
2023		4.8
	$	62.1

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

ASC Topic 820, Fair Value Measurements and Disclosures, requires disclosure of the fair value of financial instruments held by the Company. ASC 825, Financial Instruments, defines fair value and establishes a three-level valuation hierarchy for disclosures of fair value measurement that enhances disclosure requirements for fair value measures. The Company’s principal financial instruments are comprised of cash, marketable securities, accounts receivable, accounts payable, accrued liabilities and long-term debt. The carrying value of all financial instruments approximates fair value. The three levels of valuation hierarchy are defined as follows:

Level 1—Inputs are based upon observable or quoted prices for identical instruments traded in active markets.

Level 2—Inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 investments consist primarily of corporate notes and bonds and U.S. government and agency securities.

Level 3—Inputs are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques that include option pricing models, discounted cash flow models, and similar techniques.

In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value.

The Company’s marketable securities consist of corporate bonds and a government bond which are adjusted to fair value at each balance sheet date, based on quoted prices, which are considered Level 2 inputs. During the three and nine months ended September 30, 2019, a non-recurring fair value measurement was applied to determine the fair value of the non-cash consideration received related to the joint venture with Bayer. The fair value measurement was determined using an income approach based primarily on utilizing management’s estimates of future cash flows as inputs which are considered Level 3 measurements within the above fair value hierarchy.

The following is a summary of the Company’s available-for-sale securities as of September 30, 2019 and December 31, 2018:

September 30, 2019				Gross		Gross
Description	Effective Maturity	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate bonds	2019	$	46,836,782		22,172		—		$	46,858,954
Government bonds	2019		2,993,900		3,757		—			2,997,657
Corporate bonds	2020-2021		128,347,831		228,074		(57,357	)		128,518,548
		$	178,178,513	$	254,003	$	(57,357	)	$	178,375,159

December 31, 2018				Gross		Gross
Description	Effective Maturity	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate bonds	2019	$	154,859,427		—		(165,630	)	$	154,693,797
Government bonds	2019		2,966,262		2,778		—			2,969,040
Corporate bonds	2020		27,029,673		—		(54,870	)		26,974,803
		$	184,855,362		2,778		(220,500	)	$	184,637,640

The following tables summarize the fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis:

September 30, 2019
Description	Level 1		Level 2		Level 3		Total
Assets:
Corporate bonds	$	—	$	175,377,502	$	—	$	175,377,502
Government bonds	$	—	$	2,997,657	$	—	$	2,997,657

December 31, 2018
Description	Level 1		Level 2		Level 3		Total
Assets:
Corporate bonds	$	—	$	181,668,600	$	—	$	181,668,600
Government bonds	$	—	$	2,969,040	$	—	$	2,969,040

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property, Equipment and Leasehold Improvements

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Property, Equipment and Leasehold Improvements

5. Property, Equipment and Leasehold Improvements

Property, equipment and leasehold improvements consist of the following at:

	September 30, 2019			December 31, 2018
Laboratory equipment	$	7,077,041		$	3,757,265
Office equipment		752,636			577,418
Leasehold improvements		2,058,972			981,884
Total		9,888,649			5,316,567
Less: accumulated depreciation and amortization		(2,736,498	)		(1,733,531	)
Property, equipment and leasehold improvements, net	$	7,152,151		$	3,583,036

Depreciation and amortization expense totaled $468,225 and $191,547 for the three months ended September 30, 2019 and 2018, respectively, and $1,024,845 and $483,052 for the nine months ended September 30, 2019 and 2018, respectively.

Right to Use Assets and Liabilities

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Right to Use Assets and Liabilities

6. Right to Use Assets and Liabilities

The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use (ROU) assets and operating lease liabilities in the condensed consolidated balance sheets.

ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The incremental borrowing rate was 5.1%. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Some of the Company’s leases include options to extend or terminate the lease. The Company includes these options in the recognition of the Company’s ROU assets and lease liabilities when it is reasonably certain that the Company will exercise the option.

The Company has operating leases for its corporate office and certain equipment, which expire no later than December 31, 2022. The leases have a weighted average remaining term of 3.2 years. Maturities of lease liabilities for the years ending December 31 are:

2019	$	141,309
2020		764,555
2021		840,498
2022		823,403
Total lease payments		2,569,765
Less: imputed interest		(204,976	)
Total	$	2,364,789

The amortization of the ROU assets for the three and nine months ended September 30, 2019 was $140,245 and $506,855, respectively.

Prior to January 1, 2019, the Company accounted for its leases in accordance with ASC Topic 840, Leases. At December 31, 2018, the Company was committed under operating leases for its corporate office and certain equipment. As previously disclosed in the Annual Report and under previous lease accounting guidance, future minimum lease payments under non-cancelable operating leases as of December 31, 2018 totaled $2,885,594, comprised of $705,606 for 2019, $731,541 for each of 2020 and 2021, and $716,906 for 2022.

Accrued Expenses

9 Months Ended

Sep. 30, 2019

Payables And Accruals [Abstract]

Accrued Expenses

7. Accrued Expenses

Accrued expenses consisted of the following at:

	September 30, 2019		December 31, 2018
Employee expenses	$	3,676,246	$	2,795,205
Research and development expenses		1,301,971		357,148
Professional fees and other		1,248,754		848,923
	$	6,226,971	$	4,001,276

Long-Term Debt

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Long-Term Debt

8. Long-Term Debt

In August 2013, the Company entered into a Loan Agreement (Loan) and a Stock Subscription Warrant, with Connecticut Innovations, Incorporated (CII). Under the Loan, the Company could draw up to $750,000 for the purpose of purchasing laboratory equipment, information technology equipment and leasehold improvements. Leasehold improvements were limited to $100,000. Interest on the Loan was compounded on a monthly basis at a rate of 7.50% per annum and was required to be paid on a monthly basis beginning on the date of the first draw of funds for 10 months, then with principal payments beginning on June 1, 2015 and payable monthly until the maturity date of July 31, 2019. The Company had the ability to prepay the amount due at any time prior to the maturity date without premium or penalty. The Loan was secured by substantially all of the Company’s assets. As of December 31, 2018, the amount outstanding under the Loan was $169,610 and the total unamortized debt discount on the Loan totaled $7,210. The Company paid the loan in full in July 2019. Interest expense recorded related to the amortization of the debt discount in the nine months ended September 30, 2019 and 2018 was $7,210 and $9,269, respectively.

In connection with the issuance of the Loan, and as additional consideration, the Company granted CII a warrant to purchase 110,116 shares of the Company’s Series A Preferred Stock at a purchase price of $0.6811 per share, with a term of 7 years from the date of issuance (CII Series A Preferred Stock Warrant). Effective January 1, 2015, the CII Series A Preferred Stock Warrant was exchanged for a warrant to purchase 110,116 units of the Company’s Series A redeemable convertible preferred units (CII Series A Preferred Unit Warrant). In July 2018, CII exercised the CII Series A Preferred Unit Warrant.

In connection with an Assistance Agreement with the State of Connecticut (Assistance Agreement) entered into in 2014, under which all the borrowings by the Company were forgiven in accordance with the Assistance Agreement, the Company is required to be located in the State of Connecticut through January 2024, with a default penalty of repayment of the full original funding amount of $2.5 million plus liquidated damages of 7.5%.

In June 2018, the Company entered into an Assistance Agreement with the State of Connecticut (2018 Assistance Agreement) to provide funding for the expansion and renovation of laboratory and office space (Project). Under the terms of the 2018 Assistance Agreement, the Company could borrow from the State of Connecticut a maximum of $2.0 million, provided that the funding does not exceed more than 50% of the total Project costs. In September 2018, the Company borrowed $2.0 million under the 2018 Assistance Agreement, bearing interest at 3.25% per annum and interest payments will be required for the first 60 months from the funding date. Thereafter, the loan amortizes over the next sixty months, maturing in September 2028. According to the terms of the 2018 Assistance Agreement, up to $1.0 million of the funding thereunder can be forgiven if the Company meets certain employment conditions, as defined therein. The Company may also be required to prepay a portion of the loan if the employment conditions are not met. The 2018 Assistance Agreement requires that the Company be located in the State of Connecticut through June 2028 with a default penalty of repayment of the full original funding amount of $2.0 million plus liquidated damages of 7.5% of the total amount of funding received.

Anticipated future minimum payments on long-term debt for the years ending December 31 are:

2023	$	92,480
2024		377,516
Beyond		1,530,004
Total	$	2,000,000

During the three months ended September 30, 2019 and 2018, interest expense was $22,903 and $12,264, respectively. During the nine months ended September 30, 2019 and 2018, interest expense was $69,319 and $32,804, respectively.

Equity

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity

9. Equity

In June 2019, the Company entered into a Stock Purchase Agreement with Bayer AG pursuant to which, in connection with the closing in July 2019, the Company issued and sold to Bayer AG 1,346,313 shares of the Company’s common stock (the Shares) for a contractually stated purchase price of approximately $32.5 million. The value of the shares of the Company’s common stock was based on the average of the Company’s common stock for the preceding 60 days prior to the signing of the Stock Purchase Agreement plus a fifteen per cent premium. The Shares are subject to lock-up restrictions, which will expire six months following the issuance date. On October 1, 2019, the Company filed a registration statement covering these shares.

In the Fourth Amendment to the Company’s Incentive Share Plan (the Incentive Plan) adopted in March 2018, the Company was authorized to issue up to an aggregate of 6,199,477 incentive units pursuant to the Incentive Plan. Generally, incentive units were granted at no less than fair value as determined by the board of managers and had vesting periods ranging from one to four years. The Incentive Plan was terminated in September 2018. In September 2018, the Company’s board of directors adopted and the Company’s stockholders approved the 2018 Stock Incentive Plan (the 2018 Plan), which became effective upon the effectiveness of the registration statement on Form S-1 for the Company’s IPO. The number of common shares initially available for issuance under the 2018 Plan is the sum of (1) 4,067,007 shares of common stock; plus (2) the number of shares of common stock (up to 1,277,181) issued in respect of incentive units granted under the Incentive Plan that are subject to vesting immediately prior to the effectiveness of the registration statement that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right; plus (3) an annual increase on the first day of each fiscal year beginning with the fiscal year ending December 31, 2019 and continuing to, and including, the fiscal year ending December 31, 2028, equal to the lowest of 4,989,593 shares of the Company’s common stock, 4% of the number of shares of the Company’s common stock outstanding on the first day of the fiscal year and an amount determined by the Company’s board of directors. The increase in the number of authorized shares for the fiscal year ending December 31, 2019 was 1,293,510. Common shares subject to outstanding equity awards that expire or are terminated, surrendered, or canceled without having been fully exercised or are forfeited in whole or in part shall be available for future grants of awards.

During the nine months ended September 30, 2019, the Company granted 1,344,337 stock options to purchase shares of common stock to employees and directors at a weighted average fair value of $12.95 per share. During the nine months ended September 30, 2019, the Company also granted 192,882 restricted stock units, which vest annually over four years.

During the nine months ended September 30, 2019, the Company recognized compensation expense of $14,049,075 relating to the issuance of employee and director incentive awards, and at September 30, 2019, there was $17,051,723 of compensation expense that is expected to be amortized over a weighted average period of approximately two years.

During the nine months ended September 30, 2019, the Company granted 51,695 stock options to purchase shares of common stock to consultants at a weighted average fair value of $23.89. During the nine months ended September 30, 2019, the Company recognized compensation expense of $1,042,194 relating to incentive share awards for consultants and at September 30, 2019, there was $1,195,887 of compensation expense remaining to be amortized over a weighted average period of approximately 1.3 years.

The fair value of the incentive units granted during the nine months ended September 30, 2018 was determined using the Black-Scholes option pricing model with the following assumptions:

	September 30, 2018
Expected volatility	66.0-71.0%
Expected term (years)	5.6-6.1
Risk free interest rate	2.5-2.9%
Expected dividend yield		0	%
Fair value of underlying common units	$1.08-8.48

The fair value of the underlying common units was utilized as the exercise price within the Black-Scholes option pricing model.

The fair value of the stock options granted during the nine months ended September 30, 2019 was determined using the Black-Scholes option pricing model with the following assumptions:

	September 30, 2019
Expected volatility	69.6-70.5%
Expected term (years)	5.5-7.0
Risk free interest rate	1.4-2.7%
Expected dividend yield		0	%
Exercise price	$17.29-26.58

Given the Company’s common stock has not been trading for a sufficient period of time, the Company utilizes a collection of volatilities of peer companies to estimate the expected volatility of its common stock. The expected term is calculated utilizing the simplified method.

The following table provides a summary of the restricted stock grant activity under the Incentive Plan during the nine months ended September 30, 2019. These amounts include restricted stock granted to employees, directors and consultants.

	Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock at December 31, 2018		1,102,289		$	16.00
Vested		(383,695	)	$	16.00
Forfeited		(46,699	)	$	16.00
Unvested restricted stock at September 30, 2019		671,895		$	16.00

The following table provides a summary of the stock option activity under the 2018 Plan during the nine months ended September 30, 2019. These amounts include stock options granted to employees, directors and consultants.

	Options			Weighted Average Fair Value
Outstanding at December 31, 2018		2,273,024		$	9.88
Granted		1,396,032		$	13.01
Exercised		(111,091	)	$	9.56
Forfeited		(159,866	)	$	11.09
Outstanding at September 30, 2019		3,398,099		$	11.11
Exercisable at September 30, 2019		903,468		$	9.86

The following table provides a summary of the restricted stock unit activity under the 2018 Plan during the nine months ended September 30, 2019. These amounts include restricted stock units granted to employees.

	Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock units at December 31, 2018		—		$	—
Granted		192,882		$	19.96
Forfeited		(11,510	)	$	19.36
Unvested restricted stock units at September 30, 2019		181,372		$	20.00

At September 30, 2019, there were 559,770 restricted shares under the Incentive Plan, 3,031,039 stock options under the 2018 Plan, and 141,381 restricted stock units under the 2018 Plan that vested and are expected to vest.

Income Taxes

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

The Company’s effective tax rate was 0.0% for the nine months ended September 30, 2019 and 2018. The primary reconciling items between the federal statutory rate of 21.0% for the nine months ended September 30, 2019 and 2018 and the Company’s overall effective tax rate of 0.0% was the effect of equity compensation and the valuation allowance recorded against the full amount of its net deferred tax assets.

Valuation allowance is established when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The realization of deferred tax assets depends on the generation of future taxable income during the period in which related temporary differences become deductible.

The Company is subject to tax in the U.S. Federal jurisdiction and the states of Connecticut and Massachusetts. The Company pays franchise tax in the states mentioned above due to its loss position. As a result, there is no state income tax provision recorded for the nine months ended September 30, 2019 and 2018.

Net Loss Per Common Share

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Net Loss Per Common Share

11. Net Loss Per Common Share

Basic and diluted loss per common share were calculated as follows:

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Net loss	$	(17,675,373	)	$	(13,387,672	)	$	(49,244,511	)	$	(25,392,600	)
Change in redemption value of preferred units		—			(112,050,609	)		—			(198,366,756	)
Net loss attributable to common shares—basic and diluted	$	(17,675,373	)	$	(125,438,281	)	$	(49,244,511	)	$	(223,759,356	)
Weighted average number of common shares outstanding, basic and diluted		32,740,486			2,010,807			31,876,074			1,935,299
Net loss per common share	$	(0.54	)	$	(62.38	)	$	(1.54	)	$	(115.62	)

The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per common share as the effect would be to reduce the net loss per common share. The following common share/unit equivalents have been excluded from the calculations of diluted loss per common share because their inclusion would have been antidilutive for the periods ended September 30:

	2019		2018
Redeemable convertible preferred units		—		19,664,047
Restricted stock		671,895		1,268,923
Stock options		3,398,099		2,181,810
Restricted stock units		181,372		—
		4,251,366		23,114,780

Investment in Equity Method Investee

9 Months Ended

Sep. 30, 2019

Equity Method Investments And Joint Ventures [Abstract]

Investment in Equity Method Investee

12. Investment in Equity Method Investee

In June 2019, the Company entered into an agreement to establish a joint venture (Commitment Agreement) with Bayer CropScience LP (Bayer LP) to research, develop and commercialize PROTAC targeted protein degraders for applications in the field of agriculture. In July 2019, the Company and Bayer LP completed the formation of the joint venture entity, Oerth Bio LLC (Oerth), a limited liability corporation. Pursuant to the terms of the Commitment Agreement, the Company made an in-kind intellectual property contribution to Oerth in the form of a license to certain of the Company’s proprietary technology. Bayer LP has made a $56.0 million total cash commitment to Oerth, $16.0 million of which Bayer LP has contributed to Oerth during the quarter ended September 30, 2019, and an in-kind intellectual property contribution. The Company and Bayer LP each hold an ownership interest in Oerth initially representing 50% of the ownership interests. A 15% ownership interest of Oerth is reserved for the future grant of incentive units to employees and service providers of Oerth.

Under the joint venture agreement, the Company has no obligation to provide any additional funding and the Company’s ownership interest will not be diluted from future contributions from Bayer LP. The Company has no exposure to future losses of Oerth. The activities of Oerth are controlled by a management board under the joint control of the Company and Bayer LP. As Oerth is jointly controlled by the Company and Bayer LP, the Company accounts for its 50% interest using the equity method of accounting. The Company determined that Oerth is a variable interest entity and, accordingly, the Company has evaluated the significant activities of Oerth under the variable interest entity model and concluded that the significant activities consist primarily of research and development activities and, as the Company does not have the sole power to direct such activities, the Company is not the primary beneficiary.

The Company will also provide to Oerth compensated research and development services and administrative services through a separate agreement. The services rendered by the Company during the three months ended September 30, 2019 were insignificant.

The Company determined that the fair value of the equity interest it received in Oerth in exchange for the license contributed was $49.4 million. The fair value of Oerth was determined utilizing discounted cash flows based on reasonable estimates and assumptions of cash flows expected from Oerth.

The Company recognized revenue of $24.7 million attributable to the license contributed to Oerth and eliminated the remaining $24.7 million which corresponds to the Company’s 50% ownership in Oerth. The Company determined that the amount that was eliminated represents intra-entity profit which should be deferred until realized by Oerth. The deferral will be recognized when Oerth recognizes revenue associated with the license. Until such time, the remaining $24.7 million of revenue is indefinitely deferred and excluded from the results of operations of the Company. The amount recognized as revenue was treated as such because the licensing of its technology in connection with the formation of a joint venture is part of the Company’s major ongoing or central operations, as evidenced by previous licensing agreements.

Total operating expenses and net loss of Oerth for the three and nine months ended September 30, 2019 was $49.5 million, which included research and development expenses equal to $49.4 million for the fair value of the Arvinas license acquired. During the three and nine months ended September 30, 2019, the Company recorded equity method losses of $24.7 million based on its proportionate share of ownership.

The Company’s initial investment in Oerth was $49.4 million which represented the fair value of shares received in exchange for the contribution of the license. The elimination of the intra-entity profit component of the revenue resulted in a reduction in the balance of the investment in Oerth, bringing its initial carrying value of the investment to $24.7 million. After recognition of its proportionate share of Oerth’s losses for the period the carrying value of the investment as of September 30, 2019 is now $0.

Related Parties

9 Months Ended

Sep. 30, 2019

Related Parties

13. Related Parties

Dr. Craig Crews, founder of the Company and the Chief Scientific Advisor to the Company, is a common shareholder in the Company and has a consulting agreement with the Company. The Company entered into an amendment to the amended and restated consulting agreement with Professor Crews, which became effective upon the closing of the IPO and continues in effect for three years, until September 26, 2021. Pursuant to the amendment, Professor Crews will be paid $20,833 per month for his services. During the nine months ended September 30, 2019 and 2018, the Company paid Professor Crews $187,500 and $113,611, respectively, related to his consulting agreement. In connection with the conversion of incentive units in connection with the IPO, the Company also granted Professor Crews 235,150 options to purchase common stock at an exercise price of $16.00 per share, vesting over three years.

In July 2016, the Company entered into a Corporate Sponsored Research Agreement (SRA) with Yale University (Yale), under the direction of Professor Crews, which was amended in April 2018. The amended SRA extended the agreement until April 2021 and amended the scope of work. The amended SRA requires quarterly payments of $250,000 through the end of the agreement. The total payments made under the SRA for the nine months ended September 30, 2019 and 2018 were $750,000 and $601,161, respectively. During the nine months ended September 30, 2019 and 2018, the Company also paid Yale $296,476 and $107,289, respectively, for reimbursable patent costs.

During the nine months ended September 30, 2019, in connection with the Company’s license agreement with Yale, the Company made payments totaling $150,000 including milestone payments of $75,000 to Yale.

In July 2019, the Company and Bayer LP completed the formation of a joint venture entity, Oerth, with each holding an initial ownership interest of 50%. See Note 12 for more information related to the joint venture

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Unaudited Interim Financial Statements	Unaudited Interim Financial Statements The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and pursuant to the rules and regulations of the Securities and Exchange Commission. The year-end condensed consolidated balance sheet data was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. These condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the years ended December 31, 2018 and 2017 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission on March 26, 2019 (the Annual Report). The condensed consolidated financial statements, in the opinion of management, reflect all normal and recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations.
Equity Method Investments	Equity Method Investments The Company accounts for investments for which it does not have a controlling interest in accordance with Accounting Standards Codification (ASC) 323, Investments – Equity Method and Joint Ventures. The Company recognizes its pro-rata share of income and losses in the investment in “Loss from equity method investment” on the consolidated statement of operations and comprehensive loss, with a corresponding change to the investment in equity method investment on the consolidated balance sheet. After recording of losses in the current period, the investment has been reduced to $0.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases. ASU 2016-02 requires lessees to present right-of-use assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. The guidance is effective for years beginning after December 15, 2018 and is to be applied using a modified retrospective approach applied at the beginning of the earliest comparative period in the financial statements or in the year of adoption with a cumulative effect to the opening balance of retained earnings. The Company adopted the new guidance as of January 1, 2019 using the modified retrospective adoption method in which it did not restate prior periods. The Company elected the practical expedient to include both lease and non-lease components as a single component and account for it as a lease. In adopting the standard, the Company also elected to utilize several other practical expedients, including not reassessing contracts for classification as a lease, not having to reassess the lease classification of existing leases, and not reassessing the initial direct costs of existing leases. The adoption of this standard resulted in the recognition of right-of-use assets and related lease liabilities of approximately $2.4 million related to its operating lease commitments on the Condensed Consolidated Balance Sheet as of January 1, 2019. In June 2018, the FASB issued ASU No. 2018-07, Improvements in Nonemployee Share-Based Payment Accounting. ASU 2018-07 aligns the accounting for share-based payment awards to nonemployees with the accounting for share-based awards to employees. ASU 2018-07 is effective for interim and annual reporting periods beginning after December 15, 2018 and early adoption is permitted. The Company adopted ASU 2018-07 in the first quarter of 2019. The adoption of the standard was immaterial to the accompanying condensed consolidated financial statements. During the three months ended September 30, 2019, there were no other changes to the Company’s significant accounting policies as described in Note 2 to the financial statements included in the Company’s condensed consolidated financial statements as of December 31, 2018 and 2017 and for the years then ended included in the Annual Report.

Research Collaboration and License Agreements (Tables)

9 Months Ended

Sep. 30, 2019

Research Collaboration And License Agreements [Abstract]

Summary of Contract Liabilities

Information about contract liabilities, which are recorded as deferred revenue on the condensed consolidated balance sheets, is as follows:

	September 30,		December 31,
	2019		2018
Contract liabilities	$	62,064,616	$	53,550,671
Revenues recognized in the period from:
Amounts included in deferred revenue in previous periods	$	12,049,468	$	13,553,136

Transaction Price Allocated to Performance Obligations

Remainder of 2019	$	6.0
2020		18.9
2021		18.7
2022		13.7
2023		4.8
	$	62.1

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Summary of Company's Available for Sale Securities

The following is a summary of the Company’s available-for-sale securities as of September 30, 2019 and December 31, 2018:

September 30, 2019				Gross		Gross
Description	Effective Maturity	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate bonds	2019	$	46,836,782		22,172		—		$	46,858,954
Government bonds	2019		2,993,900		3,757		—			2,997,657
Corporate bonds	2020-2021		128,347,831		228,074		(57,357	)		128,518,548
		$	178,178,513	$	254,003	$	(57,357	)	$	178,375,159

December 31, 2018				Gross		Gross
Description	Effective Maturity	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate bonds	2019	$	154,859,427		—		(165,630	)	$	154,693,797
Government bonds	2019		2,966,262		2,778		—			2,969,040
Corporate bonds	2020		27,029,673		—		(54,870	)		26,974,803
		$	184,855,362		2,778		(220,500	)	$	184,637,640

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables summarize the fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis:

September 30, 2019
Description	Level 1		Level 2		Level 3		Total
Assets:
Corporate bonds	$	—	$	175,377,502	$	—	$	175,377,502
Government bonds	$	—	$	2,997,657	$	—	$	2,997,657

December 31, 2018
Description	Level 1		Level 2		Level 3		Total
Assets:
Corporate bonds	$	—	$	181,668,600	$	—	$	181,668,600
Government bonds	$	—	$	2,969,040	$	—	$	2,969,040

Property, Equipment and Leasehold Improvements (Tables)

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Schedule of Property, Equipment and Leasehold Improvements

Property, equipment and leasehold improvements consist of the following at:

	September 30, 2019			December 31, 2018
Laboratory equipment	$	7,077,041		$	3,757,265
Office equipment		752,636			577,418
Leasehold improvements		2,058,972			981,884
Total		9,888,649			5,316,567
Less: accumulated depreciation and amortization		(2,736,498	)		(1,733,531	)
Property, equipment and leasehold improvements, net	$	7,152,151		$	3,583,036

Right to Use Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of Maturities of Lease Liabilities

Maturities of lease liabilities for the years ending December 31 are

2019	$	141,309
2020		764,555
2021		840,498
2022		823,403
Total lease payments		2,569,765
Less: imputed interest		(204,976	)
Total	$	2,364,789

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2019

Payables And Accruals [Abstract]

Components of Accrued Expenses

Accrued expenses consisted of the following at:

	September 30, 2019		December 31, 2018
Employee expenses	$	3,676,246	$	2,795,205
Research and development expenses		1,301,971		357,148
Professional fees and other		1,248,754		848,923
	$	6,226,971	$	4,001,276

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Schedule of Anticipated Future Minimum Payments on Long-Term Debt Excluding Discount on Debt

Anticipated future minimum payments on long-term debt for the years ending December 31 are:

2023	$	92,480
2024		377,516
Beyond		1,530,004
Total	$	2,000,000

Equity (Tables)

9 Months Ended

Sep. 30, 2019

Schedule of Assumptions Used to Determine Fair Value of Incentive Common Units Granted

The fair value of the incentive units granted during the nine months ended September 30, 2018 was determined using the Black-Scholes option pricing model with the following assumptions:

	September 30, 2018
Expected volatility	66.0-71.0%
Expected term (years)	5.6-6.1
Risk free interest rate	2.5-2.9%
Expected dividend yield		0	%
Fair value of underlying common units	$1.08-8.48

Schedule of Assumptions Used to Determine Fair Value of Stock Options Granted

The fair value of the stock options granted during the nine months ended September 30, 2019 was determined using the Black-Scholes option pricing model with the following assumptions:

	September 30, 2019
Expected volatility	69.6-70.5%
Expected term (years)	5.5-7.0
Risk free interest rate	1.4-2.7%
Expected dividend yield		0	%
Exercise price	$17.29-26.58

Summary of Restricted Stock Grant Activity

	Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock at December 31, 2018		1,102,289		$	16.00
Vested		(383,695	)	$	16.00
Forfeited		(46,699	)	$	16.00
Unvested restricted stock at September 30, 2019		671,895		$	16.00

Summary of Stock Option Activity

	Options			Weighted Average Fair Value
Outstanding at December 31, 2018		2,273,024		$	9.88
Granted		1,396,032		$	13.01
Exercised		(111,091	)	$	9.56
Forfeited		(159,866	)	$	11.09
Outstanding at September 30, 2019		3,398,099		$	11.11
Exercisable at September 30, 2019		903,468		$	9.86

Restricted Stock Units

Summary of Restricted Stock Grant Activity

	Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock units at December 31, 2018		—		$	—
Granted		192,882		$	19.96
Forfeited		(11,510	)	$	19.36
Unvested restricted stock units at September 30, 2019		181,372		$	20.00

Net Loss Per Common Share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Basic and Diluted Loss per Common Share

Basic and diluted loss per common share were calculated as follows:

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Net loss	$	(17,675,373	)	$	(13,387,672	)	$	(49,244,511	)	$	(25,392,600	)
Change in redemption value of preferred units		—			(112,050,609	)		—			(198,366,756	)
Net loss attributable to common shares—basic and diluted	$	(17,675,373	)	$	(125,438,281	)	$	(49,244,511	)	$	(223,759,356	)
Weighted average number of common shares outstanding, basic and diluted		32,740,486			2,010,807			31,876,074			1,935,299
Net loss per common share	$	(0.54	)	$	(62.38	)	$	(1.54	)	$	(115.62	)

Common Share/Unit Equivalents Excluded from the Calculations of Diluted Loss Per Common Share

The following common share/unit equivalents have been excluded from the calculations of diluted loss per common share because their inclusion would have been antidilutive for the periods ended September 30:

	2019		2018
Redeemable convertible preferred units		—		19,664,047
Restricted stock		671,895		1,268,923
Stock options		3,398,099		2,181,810
Restricted stock units		181,372		—
		4,251,366		23,114,780

Nature of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended
	Oct. 01, 2018	Oct. 31, 2018
Nature Of Business [Line Items]
Underwriting fees and expenses	$ 12.0
Preferred stock outstanding	0
Common Stock
Nature Of Business [Line Items]
Gross proceeds from sale of shares in Initial public offering before fees and expenses	$ 123.2
Common stock issued for conversion of convertible preferred stock	19,697,928
Common Stock \| Initial Public Offering
Nature Of Business [Line Items]
Stock Issued During Period, Shares, New Issues	7,500,000
Share price, issued and sold	$ 16.00
Common Stock \| Over-Allotment Option
Nature Of Business [Line Items]
Stock Issued During Period, Shares, New Issues		200,482
Share price, issued and sold		$ 16.00

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Sep. 30, 2019	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Equity method investments	$ 0
Operating lease right of use assets	2,257,544
Lease liabilities	$ 2,364,789
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease right of use assets		$ 2,400,000
Lease liabilities		$ 2,400,000

Research Collaboration and License Agreements - Additional Information (Details)	1 Months Ended	4 Months Ended	9 Months Ended
	Nov. 30, 2017 USD ($) Target	Dec. 31, 2015 USD ($)	Sep. 30, 2019 USD ($) Contract	Sep. 30, 2018 USD ($)	Dec. 31, 2022 USD ($)	Jul. 31, 2019 USD ($)
Research Collaboration And License Agreements [Line Items]
Revenue recognized on research collaboration and license agreements			$ 13,400,000
Changes in deferred revenue due to additions to deferred revenue			8,513,945	$ (7,883,755)
Unsatisfied performance obligations expected to be recognized as revenue			62,100,000
Pfizer, Inc.
Research Collaboration And License Agreements [Line Items]
Upfront non-refundable payment and certain additional payments received			28,000,000
Pfizer, Inc. \| Option Exercised
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised			2,500,000
Pfizer, Inc. \| Option Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised			37,500,000
Pfizer, Inc. \| Development Milestone Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised			225,000,000
Pfizer, Inc. \| Sales-based Milestone Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised			550,000,000
Genentech, Inc. and F. Hoffman-La Roche Ltd.
Research Collaboration And License Agreements [Line Items]
Upfront non-refundable payment and certain additional payments received	$ 34,500,000	$ 11,000,000
Number of designated targets \| Target	10
Genentech, Inc. and F. Hoffman-La Roche Ltd. \| Option Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	$ 27,500,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. \| Development Milestone Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	44,000,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. \| Regulatory Milestone Payments
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	52,500,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. \| Commercial Milestones
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	$ 60,000,000
Bayer Collaboration Agreement
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised						$ 17,500,000
Changes in deferred revenue due to additions to deferred revenue			21,900,000
Bayer Collaboration Agreement \| Development Milestone Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised						197,500,000
Bayer Collaboration Agreement \| Sales-based Milestone Payments \| Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised						490,000,000
Bayer Collaboration Agreement \| Research Funding Payments
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised						$ 1,500,000
Bayer Collaboration Agreement \| Research Funding Payments \| Scenario Forecast
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised					$ 10,500,000
Bayer Collaboration Agreement \| Stock Purchase Agreement
Research Collaboration And License Agreements [Line Items]
Fair value of the shares sold			2,900,000
Additional consideration received			$ 2,900,000
Number of contracts to be combined \| Contract			2

Research Collaboration and License Agreements - Summary of Contract Liabilities (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Contract liabilities	$ 62,064,616	$ 53,550,671
Amounts included in deferred revenue in previous periods	$ 12,049,468	$ 13,553,136

Research Collaboration and License Agreements - Transaction Price Allocated to Performance Obligations (Details) $ in Millions	Sep. 30, 2019 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 62.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 6.0
Revenue, remaining performance obligation, expected timing of satisfaction, period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 18.9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 18.7
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 13.7
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 4.8
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year

Research Collaboration and License Agreements - Transaction Price Allocated to Performance Obligations (Details1) $ in Millions	Sep. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Revenue, remaining performance obligation	$ 62.1

Fair Value Measurements - Summary of Company's Available for Sale Securities (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 178,178,513	$ 184,855,362
Gross Unrealized Gains	254,003	2,778
Gross Unrealized Losses	(57,357)	(220,500)
Fair Value	$ 178,375,159	$ 184,637,640
Corporate Bonds \| 2019
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2019	2019
Amortized Cost	$ 46,836,782	$ 154,859,427
Gross Unrealized Gains	22,172
Gross Unrealized Losses		(165,630)
Fair Value	46,858,954	$ 154,693,797
Corporate Bonds \| 2020-2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	128,347,831
Gross Unrealized Gains	228,074
Gross Unrealized Losses	(57,357)
Fair Value	$ 128,518,548
Corporate Bonds \| 2020
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity		2020
Amortized Cost		$ 27,029,673
Gross Unrealized Losses		(54,870)
Fair Value		$ 26,974,803
Corporate Bonds \| Minimum \| 2020-2021
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2020
Corporate Bonds \| Maximum \| 2020-2021
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2021
Government Securities \| 2019
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2019	2019
Amortized Cost	$ 2,993,900	$ 2,966,262
Gross Unrealized Gains	3,757	2,778
Fair Value	$ 2,997,657	$ 2,969,040

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Assets:
Fair value measurements of assets	$ 178,375,159	$ 184,637,640
Corporate Bonds \| Fair Value, Measurements, Recurring
Assets:
Fair value measurements of assets	175,377,502	181,668,600
Corporate Bonds \| Fair Value, Measurements, Recurring \| Level 2
Assets:
Fair value measurements of assets	175,377,502	181,668,600
Government Securities \| Fair Value, Measurements, Recurring
Assets:
Fair value measurements of assets	2,997,657	2,969,040
Government Securities \| Fair Value, Measurements, Recurring \| Level 2
Assets:
Fair value measurements of assets	$ 2,997,657	$ 2,969,040

Property, Equipment and Leasehold Improvements - Schedule of Property, Equipment and Leasehold Improvements (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	$ 9,888,649	$ 5,316,567
Less: accumulated depreciation and amortization	(2,736,498)	(1,733,531)
Property, equipment and leasehold improvements, net	7,152,151	3,583,036
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	7,077,041	3,757,265
Office Equipment
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	752,636	577,418
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	$ 2,058,972	$ 981,884

Property, Equipment and Leasehold Improvements - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 468,225	$ 191,547	$ 1,024,845	$ 483,052

Right to Use Assets and Liabilities - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Leases [Abstract]
Percentage of incremental borrowing for lease Payments	5.10%	5.10%
Operating lease, existence of option to extend		true
Operating lease, existence of option to terminate		true
Operating lease, weighted average remaining lease term	3 years 2 months 12 days	3 years 2 months 12 days
Operating lease expiration date		Dec. 31, 2022
Amortization of right to use assets	$ 140,245	$ 506,855	$ 0
Future minimum annual lease payments, 2019				$ 705,606
Future minimum annual lease payments, 2020				731,541
Future minimum annual lease payments, 2021				731,541
Future minimum annual lease payments, 2022				716,906
Future minimum lease payments , Total				$ 2,885,594

Right to Use Assets and Liabilities - Schedule of Maturities of Lease Liabilities (Details)	Sep. 30, 2019 USD ($)
Leases [Abstract]
2019	$ 141,309
2020	764,555
2021	840,498
2022	823,403
Total lease payments	2,569,765
Less: imputed interest	(204,976)
Lease liabilities	$ 2,364,789

Accrued Expenses - Components of Accrued Expenses (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Employee expenses	$ 3,676,246	$ 2,795,205
Research and development expenses	1,301,971	357,148
Professional fees and other	1,248,754	848,923
Accrued expenses	$ 6,226,971	$ 4,001,276

Long-Term Debt - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Aug. 31, 2013	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2014	Dec. 31, 2018	Jan. 01, 2015
Debt Instrument [Line Items]
Debt instrument, outstanding amount				$ 2,000,000		$ 2,000,000
Total unamortized debt discount on Loan									$ 7,210
Amortization of debt discount						7,210	$ 9,269
Interest expense, Debt				$ 22,903	$ 12,264	$ 69,319	$ 32,804
2014 Assistance Agreement \| State of Connecticut
Debt Instrument [Line Items]
Debt instrument maturity month and year								2024-01
Debt instrument face amount								$ 2,500,000
Percentage of liquidated damages								7.50%
2018 Assistance Agreement \| State of Connecticut
Debt Instrument [Line Items]
Debt instrument, interest rate per annum	3.25%				3.25%		3.25%
Debt instrument maturity month and year	2028-09
Debt instrument face amount	$ 2,000,000				$ 2,000,000		$ 2,000,000
Percentage of liquidated damages	7.50%
Percentage of maximum funding on total project costs		50.00%
Debt instrument interest payments term	60 months
Debt instrument amortization period after interest payments period	60 months
2018 Assistance Agreement \| State of Connecticut \| Maximum
Debt Instrument [Line Items]
Debt instrument face amount		$ 2,000,000
Forgiveness of funding on achieving certain employment conditions	$ 1,000,000
Series A Preferred Unit Warrant
Debt Instrument [Line Items]
Warrant to purchase of stock			110,116
Warrant purchase price per share			$ 0.6811
Term of warrant from the date of issuance			7 years
Series A Redeemable Convertible Preferred Units
Debt Instrument [Line Items]
Warrant to purchase of stock										110,116
Loan Agreement \| Connecticut Innovations, Inc. \| Secured Debt
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity			$ 750,000
Debt instrument, frequency of periodic payment						monthly
Debt instrument, interest rate per annum			7.50%
Debt instrument, interest only payment period upon first draw of funds			10 months
Debt instrument, date of first required payment			Jun. 01, 2015
Debt instrument, maturity date			Jul. 31, 2019
Debt instrument, outstanding amount									$ 169,610
Loan Agreement \| Connecticut Innovations, Inc. \| Secured Debt \| Leasehold Improvements
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity			$ 100,000

Long-Term Debt - Schedule of Anticipated Future Minimum Payments on Long-Term Debt Excluding Discount on Debt (Details)	Sep. 30, 2019 USD ($)
Long Term Debt By Maturity [Abstract]
2023	$ 92,480
2024	377,516
Beyond	1,530,004
Total	$ 2,000,000

Equity - Additional Information (Details) - USD ($)	1 Months Ended			9 Months Ended	12 Months Ended
Equity - Additional Information (Details) - USD ($)	Jul. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Dec. 31, 2019
Bayer A G
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues	1,346,313
Common stock issued in period	$ 32,500,000
Average common stock preceding days	60 days
Prior to stock purchase agreement premium	15.00%
Expiration period	6 months
Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive units authorized for issuance			6,199,477
Share-based award, expiration date			Sep. 30, 2018
Weighted average fair value of stock options granted				$ 12.95
Incentive Plan \| Employees And Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense				$ 14,049,075
Compensation expense not yet recognized				$ 17,051,723
Compensation expense not yet recognized, period of recognition				2 years
Incentive Plan \| Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of stock options granted				$ 23.89
Compensation expense				$ 1,042,194
Compensation expense not yet recognized				$ 1,195,887
Compensation expense not yet recognized, period of recognition				1 year 3 months 18 days
Incentive Plan \| Incentive Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, stock options granted				1,344,337
Incentive Plan \| Incentive Units \| Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, stock options granted				51,695
Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period				4 years
Share-based award, non-option equity instruments granted				192,882
Incentive Plan \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares vested and expected to vest				559,770
Incentive Plan \| Scenario Forecast
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive units authorized for issuance					1,293,510
Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period			1 year
Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period			4 years
Available for issuance of common stock		1,277,181
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Available for issuance of common stock		4,067,007
Annual increase in reserved shares as percentage of outstanding common stock		4.00%
Share-based award, stock options granted				1,396,032
Weighted average fair value of stock options granted				$ 13.01
Stock options vested and expected to vest				3,031,039
Restricted stock units vested and expected to vest				141,381
2018 Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in reserved shares of common stock		4,989,593

Equity - Schedule of Assumptions Used to Determine Fair Value of Incentive Common Units Granted (Details) - Incentive Common Units	9 Months Ended
	Sep. 30, 2018 $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	66.00%
Expected volatility, maximum	71.00%
Risk free interest rate, minimum	2.50%
Risk free interest rate, maximum	2.90%
Expected dividend yield	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 7 months 6 days
Fair value of underlying common units	$ 1.08
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days
Fair value of underlying common units	$ 8.48

Equity - Schedule of Assumptions Used to Determine Fair Value of and Stock Options Granted (Details) - Stock Options	9 Months Ended
	Sep. 30, 2019 $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	69.60%
Expected volatility, maximum	70.50%
Risk free interest rate, minimum	1.40%
Risk free interest rate, maximum	2.70%
Expected dividend yield	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months
Fair value of underlying common units	$ 17.29
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	7 years
Fair value of underlying common units	$ 26.58

Equity - Summary of Restricted Stock Grant Activity (Details) - Incentive Plan	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Restricted Stock \| Employees, Directors and Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested Restricted Stock, Shares, Beginning Balance	1,102,289
Restricted Shares, Vested	(383,695)
Restricted Shares, Forfeited	(46,699)
Unvested Restricted Stock, Shares, Ending Balance	671,895
Weighted Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 16.00
Weighted Average Grant Date Fair Value Per Share, Granted \| $ / shares	16.00
Weighted Average Grant Date Fair Value Per Share, Forfeited \| $ / shares	16.00
Weighted Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 16.00
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Shares, Granted	192,882
Restricted Stock Units \| Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested Restricted Stock, Shares, Beginning Balance	0
Restricted Shares, Granted	192,882
Restricted Shares, Forfeited	(11,510)
Unvested Restricted Stock, Shares, Ending Balance	181,372
Weighted Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 0
Weighted Average Grant Date Fair Value Per Share, Granted \| $ / shares	19.96
Weighted Average Grant Date Fair Value Per Share, Forfeited \| $ / shares	19.36
Weighted Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 20.00

Equity - Summary of Stock Option Activity (Details) - 2018 Plan	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding, Beginning Balance \| shares	2,273,024
Options, Granted \| shares	1,396,032
Options, Exercised \| shares	(111,091)
Options, Forfeited \| shares	(159,866)
Options, Outstanding, Ending Balance \| shares	3,398,099
Options, Exercisable, Ending Balance \| shares	903,468
Weighted Average Fair Value, Outstanding, Beginning Balance \| $ / shares	$ 9.88
Weighted Average Fair Value, Granted \| $ / shares	13.01
Weighted Average Fair Value, Exercised \| $ / shares	9.56
Weighted Average Fair Value, Forfeited \| $ / shares	11.09
Weighted Average Fair Value, Outstanding, Ending Balance \| $ / shares	11.11
Weighted Average Fair Value, Exercisable, Ending Balance \| $ / shares	$ 9.86

Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate, percentage	0.00%	0.00%
Federal statutory rate, percentage	21.00%	21.00%
Effect of equity compensation valuation allowance recorded against net deferred tax assets, percentage	0.00%
State income tax provision	$ 0	$ 0

Net Loss Per Common Share - Basic and Diluted Loss per Common Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net loss	$ (17,675,373)	$ (13,387,672)	$ (49,244,511)	$ (25,392,600)
Change in redemption value of preferred units	0	(112,050,609)	0	(198,366,756)
Net loss attributable to common shares—basic and diluted	$ (17,675,373)	$ (125,438,281)	$ (49,244,511)	$ (223,759,356)
Weighted average number of common shares outstanding, basic and diluted	32,740,486	2,010,807	31,876,074	1,935,299
Net loss per common share	$ (0.54)	$ (62.38)	$ (1.54)	$ (115.62)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Loss Per Common Share - Common Share/Unit Equivalents Excluded from the Calculations of Diluted Loss Per Common Share (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share	4,251,366	23,114,780
Redeemable Convertible Preferred Stock/Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share		19,664,047
Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share	671,895	1,268,923
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share	3,398,099	2,181,810
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share	181,372

Investment in Equity Method Investee - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jul. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Revenue recognized			$ 12,049,468		$ 13,553,136
Deferred revenue	$ 62,064,616		62,064,616		$ 53,550,671
Loss from equity method investment	(24,675,000)	$ 0	(24,675,000)	$ 0
Equity method investments	0		0
Oerth
Schedule Of Equity Method Investments [Line Items]
Cash commitment	$ 49,400,000		$ 49,400,000
Ownership interest in joint venture	50.00%		50.00%			50.00%
Future grant of incentive units to service providers, percentage	15.00%		15.00%
Revenue recognized			$ 24,700,000
Deferred revenue	$ 24,700,000		24,700,000
Research and development expenses	49,400,000		49,400,000
Operating expenses	49,500,000		49,500,000
Net loss	(49,500,000)		(49,500,000)
Loss from equity method investment	(24,700,000)		(24,700,000)
Equity method investments	0		0
Bayer LP \| Oerth
Schedule Of Equity Method Investments [Line Items]
Cash commitment	56,000,000		$ 56,000,000
Contributed to joint venture entity	$ 16,000,000
Ownership interest in joint venture	50.00%		50.00%			50.00%

Related Parties - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jul. 31, 2019
Oerth
Related Party Transaction [Line Items]
Ownership interest in joint venture	50.00%		50.00%
Bayer LP \| Oerth
Related Party Transaction [Line Items]
Ownership interest in joint venture	50.00%		50.00%
Yale University
Related Party Transaction [Line Items]
Reimbursable patent costs	$ 296,476	$ 107,289
Payment for license agreement	150,000
Milestone payment	$ 75,000
Consulting Agreement
Related Party Transaction [Line Items]
Consulting agreement maturity date	Sep. 26, 2021
Consulting Agreement \| Dr. Craig Crews
Related Party Transaction [Line Items]
Payment for consulting service	$ 187,500	113,611
Monthly consulting services fee	$ 20,833
Consulting agreement term	3 years
Consulting Agreement \| Dr. Craig Crews \| Initial Public Offering
Related Party Transaction [Line Items]
Share-based award, stock options granted	235,150
Exercise price of stock options	$ 16.00
Incentive units vesting period	3 years
Amended Corporate Sponsored Research Agreement \| Yale University
Related Party Transaction [Line Items]
Quarterly research payments	$ 250,000
Corporate Sponsored Research Agreement (SRA) \| Yale University
Related Party Transaction [Line Items]
Total research payments	$ 750,000	$ 601,161
Related party agreement, description	In July 2016, the Company entered into a Corporate Sponsored Research Agreement (SRA) with Yale University (Yale), under the direction of Professor Crews, which was amended in April 2018. The amended SRA extended the agreement until April 2021 and amended the scope of work. The amended SRA requires quarterly payments of $250,000 through the end of the agreement. The total payments made under the SRA for the nine months ended September 30, 2019 and 2018 were $750,000 and $601,161, respectively