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Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2020	May 01, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2020
Entity File Number	001-36112
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Registrant Name	MACROGENICS, INC.
Entity Central Index Key	0001125345
Current Fiscal Year End Date	--12-31
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Small Business	false
Local Phone Number	251-5172
City Area Code	301
Trading Symbol	MGNX
Security Exchange Name	NASDAQ
Entity Address, Postal Zip Code	20850
Entity Tax Identification Number	06-1591613
Entity Incorporation, State or Country Code	DE
Entity Common Stock, Shares Outstanding		49,138,017
Entity Address, Address Line One	9704 Medical Center Drive
Entity Address, City or Town	Rockville
Entity Address, State or Province	MD
Amendment Flag	false
Entity Shell Company	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 93,056	$ 126,472
Marketable securities	77,793	89,284
Accounts receivable	11,806	12,744
Prepaid expenses and other current assets	12,630	11,285
Total current assets	195,285	239,785
Property, equipment and software, net	46,318	48,211
Other assets	23,810	24,505
Total assets	265,413	312,501
Current liabilities:
Accounts payable	1,956	4,308
Accrued expenses and other current liabilities	25,060	27,139
Deferred revenue	9,506	10,700
Lease liabilities	3,088	3,020
Total current liabilities	39,610	45,167
Deferred revenue, net of current portion	8,100	9,153
Lease liabilities, net of current portion	26,615	27,553
Other non current liabilities	515	0
Total liabilities	74,840	81,873
Stockholders' equity:
Common stock, $0.01 par value -- 125,000,000 shares authorized, 49,131,150 and 48,958,763 shares outstanding at March 31, 2020 and December 31, 2019, respectively	492	490
Additional paid-in capital	876,815	872,204
Accumulated other comprehensive income	72	16
Accumulated deficit	(686,806)	(642,082)
Total stockholders' equity	190,573	230,628
Total liabilities and stockholders' equity	$ 265,413	$ 312,501

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Revenues	$ 13,682	$ 9,662
Costs and expenses:
Research and development	48,894	47,060
General and administrative	10,233	10,219
Total costs and expenses	59,127	57,279
Loss from operations	(45,445)	(47,617)
Other income	721	2,600
Net loss	(44,724)	(45,017)
Other comprehensive income:
Unrealized gain on investments	56	3
Comprehensive loss	$ (44,668)	$ (45,014)
Basic and diluted net loss per common share (in usd per share)	$ (0.91)	$ (0.99)
Basic and diluted weighted average common shares outstanding (in shares)	49,012,663	45,606,651
Revenue From Collaborative Agreements
Revenues:
Revenues	$ 12,967	$ 9,497
Revenue From Government Agreements
Revenues:
Revenues	$ 715	$ 165

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2018		42,353,301
Beginning balance at Dec. 31, 2018	$ 242,877	$ 424	$ 732,727	$ (490,271)	$ (3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,750		3,750
Issuance of common stock, net of offering costs (in shares)		6,325,000
Issuance of common stock, net of offering costs	118,657	$ 63	118,594
Stock plan related activity (in shares)		126,707
Stock plan related activity	347	$ 1	346
Unrealized gain (loss) on investments	3				3
Net loss	(45,017)			(45,017)
Ending balance (in shares) at Mar. 31, 2019		48,805,008
Ending balance at Mar. 31, 2019	320,617	$ 488	855,417	(535,288)	0
Beginning balance (in shares) at Dec. 31, 2019		48,958,763
Beginning balance at Dec. 31, 2019	230,628	$ 490	872,204	(642,082)	16
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	$ 4,451		4,451
Stock plan related activity (in shares)	1,403,627	172,387
Stock plan related activity	$ 162	$ 2	160
Unrealized gain (loss) on investments	56				56
Net loss	(44,724)			(44,724)
Ending balance (in shares) at Mar. 31, 2020		49,131,150
Ending balance at Mar. 31, 2020	$ 190,573	$ 492	$ 876,815	$ (686,806)	$ 72

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net loss	$ (44,724)	$ (45,017)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	2,809	2,903
Stock-based compensation	4,491	3,799
Changes in operating assets and liabilities:
Accounts receivable	938	23,468
Prepaid expenses	(1,345)	(1,902)
Other assets	695	(2,079)
Accounts payable	(2,286)	(2,531)
Accrued expenses	(2,118)	(4,297)
Lease liabilities	(869)	1,086
Deferred revenue	(2,248)	(5,430)
Other liabilities	515	0
Net cash used in operating activities	(44,142)	(30,000)
Cash flows from investing activities
Purchases of marketable securities	(61,186)	(81,597)
Proceeds from sale and maturities of marketable securities	73,003	12,780
Purchases of property and equipment	(1,253)	(1,675)
Net cash provided by (used in) investing activities	10,564	(70,492)
Cash flows from financing activities
Proceeds from issuance of common stock, net of offering costs	0	118,657
Proceeds from stock option exercises and ESPP purchases	162	348
Net cash provided by financing activities	162	119,005
Net change in cash and cash equivalents	(33,416)	18,513
Cash and cash equivalents at beginning of period	126,472	220,128
Cash and cash equivalents at end of period	93,056	238,641
Supplemental Cash Flow Information [Abstract]
Right-of-use assets modified in exchange for operating lease obligations	$ 0	$ 1,988

Basis of Presentation and Liquidity	3 Months Ended
Basis of Presentation and Liquidity	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Liquidity	Basis of Presentation and Liquidity Basis of Presentation The accompanying unaudited interim consolidated financial statements of MacroGenics, Inc. (the Company) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiaries, MacroGenics UK Limited and MacroGenics Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2019 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2020. Liquidity The Company’s multiple product candidates currently under development will require significant additional research and development efforts that include extensive preclinical studies and clinical testing, and regulatory approval prior to commercial use. As a clinical-stage biotechnology company, the Company has primarily funded its operations with proceeds from the sale of its common stock in equity offerings, revenue from its multiple collaboration agreements, and contracts and grants from the National Institute of Allergy and Infectious Diseases (NIAID). Management regularly reviews the Company’s available liquidity relative to its operating budget and forecast to monitor the sufficiency of the Company’s working capital, and anticipates continuing to draw upon available sources of capital to support its product development activities. Based on the Company’s most recent cash flow forecast, the Company believes its current cash, cash equivalents and marketable securities, along with the anticipated and potential revenue under its multiple collaboration agreements, is sufficient to fund its operating plans for a minimum of twelve months from the date that this Quarterly Report was filed. The Company plans to meet its near-term operating requirements primarily through cash and marketable securities on hand, and a combination of current and future strategic collaborations and alliances and marketing, distribution or licensing arrangements. In the longer term, the Company plans to meet its operating requirements by generating revenue from product sales, to the extent its product candidates receive marketing approval and can be commercialized, or by potential future equity or debt issuances (including its at-the-market sales agreement). There can be no assurances that new sources of capital will be available to the Company on commercially acceptable terms, if at all. Also, any future collaborations, strategic alliances and marketing, distribution or licensing arrangements may require the Company to give up some or all rights to a product or technology at less than its full potential value. If the Company is unable to enter into new arrangements or to perform under current or future agreements or obtain additional capital, the Company will assess its capital resources and may be required to delay, reduce the scope of, or eliminate one or more of its product research and development programs or clinical studies, and/or downsize its organization. In addition to the factors noted above, there can be no assurances regarding the potential impact of the COVID-19 pandemic crisis and its economic effects on the Company’s ability to raise capital in the future.

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

The Company's financial instruments consist of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. The carrying amount of accounts receivable, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of their short-term nature. The Company accounts for recurring and non-recurring fair value measurements in accordance with Financial Accounting Standards Board Accounting Standards Codification (ASC) 820, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value, establishes a fair value hierarchy for assets and liabilities measured at fair value, and requires expanded disclosures about fair value measurements. The ASC 820 hierarchy ranks the quality of reliability of inputs, or assumptions, used in the determination of fair value and requires assets and liabilities carried at fair value to be classified and disclosed in one of the following three categories:

•Level 1 - Fair value is determined by using unadjusted quoted prices that are available in active markets for identical assets and liabilities.

•Level 2 - Fair value is determined by using inputs other than Level 1 quoted prices that are directly or indirectly observable. Inputs can include quoted prices for similar assets and liabilities in active markets or quoted prices for identical assets and liabilities in inactive markets. Related inputs can also include those used in valuation or other pricing models, such as interest rates and yield curves that can be corroborated by observable market data.

•Level 3 - Fair value is determined by inputs that are unobservable and not corroborated by market data. Use of these inputs involves significant and subjective judgments to be made by a reporting entity - e.g., determining an appropriate adjustment to a discount factor for illiquidity associated with a given security.

The Company evaluates financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level at which to classify them each reporting period. This determination requires the Company to make subjective judgments as to the significance of inputs used in determining fair value and where such inputs lie within the ASC 820 hierarchy.

Financial assets measured at fair value on a recurring basis were as follows (in thousands):


	Fair Value Measurements at March 31, 2020
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	74,483	$	74,483	$	—	$	—

Government-sponsored enterprises	13,748		—		13,748		—
Corporate debt securities	75,040		—		75,040		—

Total assets measured at fair value^(a)	$	163,271	$	74,483	$	88,788	$	—


	Fair Value Measurements at December 31, 2019
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	46,149	$	46,149	$	—	$	—

Government-sponsored enterprises	13,222		—		13,222		—
Corporate debt securities	103,135		—		103,135		—

Total assets measured at fair value^(b)	$	162,506	$	46,149	$	116,357	$	—

(a) Total assets measured at fair value at March 31, 2020 includes approximately $85.5 million reported in cash and cash equivalents on the consolidated balance sheet.

(b) Total assets measured at fair value at December 31, 2019 includes approximately $73.2 million reported in cash and cash equivalents on the consolidated balance sheet.

The fair value of Level 2 securities is determined from market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These inputs either represent quoted prices for similar assets in active markets or have been derived from observable market data. There were no transfers between levels during the periods presented.

- 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

Collaboration and Other Agreements	3 Months Ended
Collaboration and Other Agreements	Mar. 31, 2020
Collaboration and License Agreements [Abstract]
Collaboration and Other Agreements	Collaboration and Other Agreements Incyte Corporation In October 2017, the Company entered into an exclusive global collaboration and license agreement with Incyte Corporation (Incyte) for retifanlimab (formerly known as MGA012 and INCMGA0012), an investigational monoclonal antibody that inhibits programmed cell death protein 1 (PD-1) (Incyte License Agreement). Incyte has obtained exclusive worldwide rights for the development and commercialization of retifanlimab in all indications, while the Company retains the right to develop its pipeline assets in combination with retifanlimab. Under the terms of the Incyte License Agreement, Incyte paid the Company an upfront payment of $150.0 million in 2017. Under the terms of the Incyte License Agreement, Incyte will lead global development of retifanlimab. Assuming successful development and commercialization of retifanlimab by Incyte, the Company could receive up to approximately $420.0 million in development and regulatory milestones and up to $330.0 million in commercial milestones. As of March 31, 2020, the Company has recognized $15.0 million in development milestones under the Incyte License Agreement. If retifanlimab is commercialized, the Company would be eligible to receive tiered royalties of 15% to 24% on any global net sales. The Company retains the right to develop its pipeline assets in combination with retifanlimab, with Incyte commercializing retifanlimab and the Company commercializing its asset(s), if any such potential combinations are approved. In addition, the Company retains the right to manufacture a portion of both companies' global commercial supply needs of retifanlimab, subject to a separate commercial supply agreement to be negotiated. Finally, Incyte funded the Company's activities related to the ongoing monotherapy clinical study and will continue to fund certain related clinical activities. The Company evaluated the Incyte License Agreement under the provisions of ASU No. 2014-09, Revenue from Contracts with Customers and all related amendments (collectively, ASC 606) and identified the following two performance obligations under the agreement: (i) the license of retifanlimab and (ii) the performance of certain clinical activities through a brief technology transfer period. The Company determined that the license and clinical activities are separate performance obligations because they are capable of being distinct, and are distinct in the context of the contract. The license has standalone functionality as it is sublicensable, Incyte has significant capabilities in performing clinical trials, and Incyte is capable of performing these activities without the Company's involvement; the Company is performing the activities during the transfer period as a matter of convenience. The Company determined that the transaction price of the Incyte License Agreement at inception was $154.0 million, consisting of the consideration to which the Company was entitled in exchange for the license and an estimate of the consideration for clinical activities to be performed. The transaction price was allocated to each performance obligation based on their relative standalone selling price. The standalone selling price of the license was determined using the adjusted market assessment approach considering similar collaboration and license agreements. The standalone selling price for the agreed-upon clinical activities to be performed was determined using the expected cost approach based on similar arrangements the Company has with other parties. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur, as they were determined to relate predominantly to the license granted to Incyte and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. During the year ended December 31, 2018, it became probable that a significant reversal of cumulative revenue would not occur for three development milestones totaling $15.0 million related to retifanlimab meeting certain clinical proof-of-concept criteria. Therefore the associated consideration was added to the estimated transaction price and was recognized as revenue. During the three months ended March 31, 2020, there were no adjustments to the transaction price of the Incyte License Agreement. The Company recognized the $150.0 million allocated to the license when it satisfied its performance obligation and transferred the license to Incyte in 2017. The $4.0 million allocated to the clinical activities was recognized over a period spanning 2017 and 2018. No revenue was recognized under the Incyte License Agreement during the three months ended March 31, 2020 and 2019. The Company also has an agreement with Incyte, which was entered into in 2018, under which the Company is to perform development and manufacturing services for Incyte’s clinical needs of retifanlimab (Incyte Clinical Supply Agreement). The Company evaluated the agreement under ASC 606 and identified one performance obligation under the agreement: to perform services related to the development and manufacturing of the clinical supply of retifanlimab. The transaction price is based on the costs incurred to develop and manufacture drug product and drug substance, and is recognized over time as the services are provided, as the performance by the Company does not create an asset with an alternative use and the Company has an enforceable right to payment for the performance completed to date. During the three months ended March 31, 2020 and 2019, the Company recognized revenue of $5.9 million and $4.0 million, respectively, for services performed under the Incyte Clinical Supply Agreement. Zai Lab In November 2018, the Company entered into a collaboration and license agreement with Zai Lab (Zai Lab Agreement) under which Zai Lab obtained regional development and commercialization rights in mainland China, Hong Kong, Macau and Taiwan (Zai Lab’s territory) for (i) margetuximab, an immune-optimized anti-HER2 monoclonal antibody, (ii) MGD013, a bispecific DART molecule designed to provide coordinate blockade of PD-1 and LAG-3 for the potential treatment of a range of solid tumors and hematological malignancies, and (iii) an undisclosed multi-specific TRIDENT molecule in preclinical development. Zai Lab will lead clinical development of these molecules in its territory. Under the terms of the Zai Lab Agreement, Zai Lab paid the Company an upfront payment of $25.0 million ($22.5 million after netting value-added tax withholdings of $2.5 million). Assuming successful development and commercialization of margetuximab, MGD013 and the TRIDENT molecule, the Company could receive up to $140.0 million in development and regulatory milestones, $4.0 million of which ($3.6 million after netting value-added tax withholdings of $0.4 million) was earned during the three months ended March 31, 2020. In addition, Zai Lab would pay the Company tiered royalties at percentage rates of mid-teens to 20% for net sales of margetuximab in Zai Lab’s territory, mid-teens for net sales of MGD013 in Zai Lab’s territory and 10% for net sales of the TRIDENT molecule in Zai Lab’s territory, which may be subject to adjustment in specified circumstances. The Company evaluated the Zai Lab Agreement under the provisions of ASC 606 and identified the following material promises under the arrangement for each of the two product candidates, margetuximab and MGD013: (i) an exclusive license to develop and commercialize the product candidate in Zai Lab’s territory and (ii) certain research and development activities. The Company determined that each license and the related research and development activities were not distinct from one another, as the license has limited value without the performance of the research and development activities. As such, the Company determined that these promises should be combined into a single performance obligation for each product candidate. Activities related to margetuximab and MGD013 are separate performance obligations from each other because they are capable of being distinct, and are distinct in the context of the contract. The Company evaluated the promises related to the TRIDENT molecule and determined they were immaterial in context of the contract, therefore there is no performance obligation related to that molecule. The Company determined that the net $22.5 million upfront payment from Zai Lab constituted the entirety of the consideration to be included in the transaction price as of the outset of the arrangement, and the transaction price was allocated to the two performance obligations based on their relative standalone selling price. The standalone selling price of the performance obligations was determined using the adjusted market assessment approach considering similar collaboration and license agreements. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable, and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to royalties will be recognized if and when the related sales occur, as they were determined to relate predominantly to the license granted to Zai Lab and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. Due to the relatively short-term nature of the recognition period, the revenue associated with the MGD013 performance obligation was recognized on a straight-line basis as the Company performed research and development activities under the agreement. The fixed consideration related to the margetuximab performance obligation is also being recognized on a straight-line basis as the Company performs research and development activities under the agreement. Straight-line recognition is materially consistent with the pattern of performance of the research and development activities of each product candidate. The variable consideration related to the margetuximab performance obligation will be recognized upon certain regulatory achievements. The Company recognized revenue of $3.6 million and $4.0 million during the three months ended March 31, 2020 and 2019, respectively, under the Zai Lab Agreement. Revenue recognized during the three months ended March 31, 2020 reflected milestone revenue, whereas revenue during the three months ended March 31, 2019 was recognition of the deferred upfront payment. At March 31, 2020 and December 31, 2019, $5.0 million of revenue was deferred under this agreement, all of which was current. During 2019, the Company entered into two agreements under which the Company is to perform manufacturing services for Zai Lab’s clinical needs of margetuximab and MGD013 (Zai Lab Clinical Supply Agreements). The Company evaluated the agreements under ASC 606 and determined that they should be accounted for as a single contract and identified two performance obligations within that contract: to perform services related to manufacturing the clinical supply of each of margetuximab and MGD013. The transaction price is based on the costs incurred to manufacture drug product and drug substance, and is recognized over time as the services are provided, as the performance by the Company does not create an asset with an alternative use and the Company has an enforceable right to payment for the performance completed to date. During the three months ended March 31, 2020, the Company recognized revenue of $1.0 million related to the Zai Lab Clinical Supply Agreements. I-Mab Biopharma In July 2019, the Company entered into a collaboration and license agreement with I-Mab Biopharma (I-Mab) to develop and commercialize enoblituzumab, an immune-optimized, anti-B7-H3 monoclonal antibody that incorporates the Company's proprietary Fc Optimization technology platform (I-Mab Agreement). I-Mab obtained regional development and commercialization rights in mainland China, Hong Kong, Macau and Taiwan (I-Mab's territory), will lead clinical development of enoblituzumab in its territories, and will participate in global studies conducted by the Company. Under the terms of the I-Mab Agreement, I-Mab paid the Company an upfront payment of $15.0 million. Assuming successful development and commercialization of enoblituzumab, the Company could receive up to $135.0 million in development and regulatory milestones. In addition, I-Mab would pay the Company tiered royalties ranging from mid-teens to 20% on annual net sales in I-Mab's territory. The Company evaluated the I-Mab Agreement under the provisions of ASC 606 and identified the following material promises under the arrangement: (i) an exclusive license to develop and commercialize enoblituzumab in I-Mab’s territories, (ii) perform certain research and development activities and (iii) conduct a chronic toxicology study. The Company determined that the license and the related research and development activities were not distinct from one another, as the license has limited value without the performance of the research and development activities. As such, the Company determined that the license and related research and development activities should be combined into a single performance obligation. The Company determined that the $15.0 million upfront payment from I-Mab constituted the entirety of the consideration to be included in the transaction price as of the outset of the arrangement for the license and related research and development activities. The Company has also determined that the chronic toxicology study is distinct from the other promises and has estimated the variable consideration of that performance obligation to be approximately $1.0 million. I-Mab will pay the Company for the cost of this study as the costs are incurred and I-Mab will be entitled to a one-time credit of eighty percent of the total amount of such costs against a future milestone, at which point the Company will reassess the transaction price for that milestone. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable, and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to royalties will be recognized if and when the related sales occur, as they were determined to relate predominantly to the license granted to I-Mab and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. Revenue under the I-Mab Agreement is being recognized using a cost-based input method according to costs incurred to date compared to estimated total costs. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligations. During the three months ended March 31, 2020, the Company recognized revenue of $1.1 million under the I-Mab Agreement. At March 31, 2020, $12.4 million of revenue was deferred under this agreement, $4.3 million of which was current and $8.1 million of which was non-current. At December 31, 2019, $13.5 million of revenue was deferred under this agreement, $4.4 million of which was current and $9.1 million of which was non-current. Provention Bio, Inc. In May 2018, the Company entered into a license agreement with Provention Bio, Inc. (Provention) pursuant to which the Company granted Provention exclusive global rights for the purpose of developing and commercializing MGD010 (renamed PRV-3279), a CD32B x CD79B DART molecule being developed for the treatment of autoimmune indications (Provention License Agreement). As partial consideration for the Provention License Agreement, Provention granted the Company a warrant to purchase shares of Provention’s common stock at an exercise price of $2.50 per share. If Provention successfully develops, obtains regulatory approval for, and commercializes PRV-3279, the Company will be eligible to receive up to $65.0 million in development and regulatory milestones and up to $225.0 million in commercial milestones. As of March 31, 2020, the Company has not recognized any milestone revenue under this agreement. If PRV-3279 is commercialized, the Company would be eligible to receive single-digit royalties on net sales of the product. The license agreement may be terminated by either party upon a material breach or bankruptcy of the other party, by Provention without cause upon prior notice to the Company, and by the Company in the event that Provention challenges the validity of any licensed patent under the agreement, but only with respect to the challenged patent. Also in May 2018, the Company entered into an asset purchase agreement with Provention pursuant to which Provention acquired the Company’s interest in teplizumab (renamed PRV-031), a monoclonal antibody being developed for the treatment of type 1 diabetes (Asset Purchase Agreement). As partial consideration for the Asset Purchase Agreement, Provention granted the Company a warrant to purchase shares of Provention’s common stock at an exercise price of $2.50 per share. If Provention successfully develops, obtains regulatory approval for, and commercializes PRV-031, the Company will be eligible to receive up to $170.0 million in regulatory milestones and up to $225.0 million in commercial milestones. As of March 31, 2020, the Company has not recognized any milestone revenue under this agreement. If PRV-031 is commercialized, the Company would be eligible to receive single-digit royalties on net sales of the product. Provention has also agreed to pay third-party obligations, including low single-digit royalties, a portion of which is creditable against royalties payable to the Company, aggregate milestone payments of up to approximately $1.3 million and other consideration, for certain third-party intellectual property under agreements Provention is assuming pursuant to the Provention Asset Purchase Agreement. Further, Provention is required to pay the Company a low double-digit percentage of certain consideration to the extent it is received in connection with a future grant of rights to PRV-031 by Provention to a third party. The Company evaluated the Provention License Agreement and Provention Asset Purchase Agreement under the provisions of ASC 606 and determined that they should be accounted for as a single contract and identified two performance obligations within that contract: (i) the license of MGD010 and (ii) the title to teplizumab. The Company determined that the transaction price of the Provention agreements was $6.1 million, based on the Black-Scholes valuation of the warrants to purchase 2,432,688 shares of Provention's common stock. The transaction price was allocated to each performance obligation based on the number of shares of common stock the Company is entitled to purchase under each warrant. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur, therefore they have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. The Company recognized revenue of $6.1 million when it satisfied its performance obligations under the agreements and transferred the MGD010 license and teplizumab assets to Provention in 2018. The warrants were revalued at each reporting period based on the current Black-Scholes parameters until the warrants were exercised in July 2019. The resulting increase or decrease in the value of the warrants is reflected in Other income (expense) on the 2019 consolidated statement of operations and comprehensive loss. In July 2019, the Company exercised the warrants on a cashless basis, and subsequently sold all the shares of Provention common stock acquired through the exercise. No shares of Provention stock were held at December 31, 2019. NIAID Contract The Company entered into a contract with NIAID, effective as of September 15, 2015, to perform product development and to advance up to two DART molecules, including MGD014 (NIAID Contract). Under the NIAID Contract, the Company will develop these product candidates for Phase 1/2 clinical trials as therapeutic agents, in combination with latency reversing treatments, to deplete cells infected with human immunodeficiency virus (HIV) infection. NIAID does not receive goods or services from the Company under this contract, therefore the Company does not consider NIAID to be a customer and concluded this contract is outside the scope of Topic 606. The NIAID Contract includes a base period of up to $7.5 million to support development of MGD014 through Investigational New Drug application submission with the U.S. Food and Drug Administration, as well as up to $17.0 million in additional development funding via NIAID options. Should NIAID fully exercise such options, the Company could receive total payments of up to $24.5 million. The total potential period of performance under the award is from September 15, 2015 through December 31, 2024. In 2017, NIAID exercised the first option in the amount of up to $10.8 million. During the three months ended March 31, 2020 and 2019, the Company recognized revenue under the NIAID Contract of $0.7 million and $0.2 million, respectively.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

Employee Stock Purchase Plan

In May 2017, the Company’s stockholders approved the 2016 Employee Stock Purchase Plan (the 2016 ESPP). The 2016 ESPP is structured as a qualified employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended (IRC), and is not subject to the provisions of the Employee Retirement Income Security Act of 1974. The Company reserved 800,000 shares of common stock for issuance under the 2016 ESPP. The 2016 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 10% of their eligible compensation, subject to any plan limitations. The 2016 ESPP provides for six-month offering periods ending on May 31 and November 30 of each year. At the end of each offering period, employees are able to purchase shares at 85% of the fair market value of the Company’s common stock on the last day of the offering period. During the three months ended March 31, 2020, no shares of common stock were purchased under the 2016 ESPP.

Employee Stock Option Plans

Effective February 2003, the Company implemented the 2003 Equity Incentive Plan (2003 Plan), and it was amended and approved by the Company's stockholders in 2005. Stock options granted under the 2003 Plan may be either incentive stock options as defined by the IRC, or non-qualified stock options. In 2013, the 2003 Plan was terminated, and no further awards may be issued under the plan. Any shares of common stock subject to awards under the 2003 Plan that expire, terminate, or are otherwise surrendered, canceled, forfeited or repurchased without having been fully exercised, or resulting in any common stock being issued, will become available for issuance under the 2013 Stock Incentive Plan (2013 Plan), up to a specified number of shares. As of March 31, 2020, under the 2003 Plan, there were options to purchase an aggregate of 376,079 shares of common stock outstanding at a weighted average exercise price of $2.96 per share.

In October 2013, the Company implemented the 2013 Plan. The 2013 Plan provides for the grant of stock options and other stock-based awards, as well as cash-based performance awards. The number of shares of common stock reserved for issuance under the 2013 Plan will automatically increase on January 1 of each year from January 1, 2014 through and including January 1, 2023, by the lesser of (a) 1,960,168 shares, (b) 4.0% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (c) the number of shares of common stock determined by the Company's Board of Directors. During the three months ended March 31, 2020, the maximum number of shares of common stock authorized to be issued by the Company under the 2013 Plan was increased to 11,896,613. If an option expires or terminates for any reason without having been fully exercised, if any shares of restricted stock are forfeited, or if any award terminates, expires or is

settled without all or a portion of the shares of common stock covered by the award being issued, such shares are available for the grant of additional awards. However, any shares that are withheld (or delivered) to pay withholding taxes or to pay the exercise price of an option are not available for the grant of additional awards. As of March 31, 2020, there were options to purchase an aggregate of 7,268,860 shares of common stock outstanding at a weighted average exercise price of $21.88 per share under the 2013 Plan.

The following stock-based compensation expense was recognized for the periods indicated (in thousands):


	Three Months Ended March 31,
	2020		2019
Research and development	$	2,434	$	1,814
General and administrative	2,057		1,985
Total stock-based compensation expense	$	4,491	$	3,799

The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated:


	Three Months Ended March 31,
	2020	2019
Expected dividend yield	0%	0%
Expected volatility	67.3% - 69.5%	73.7% - 74.4%
Risk-free interest rate	0.6% - 1.8%	2.3% - 2.6%
Expected term	6.25 years	6.25 years

For periods through December 31, 2019, the computation of expected volatility is based on the historical volatility of several public entities of similar size, complexity and stage of development, as the Company did not have sufficient history of its own volatility. As of December 31, 2019, the Company had sufficient company-specific historical and implied volatility information. As such, beginning the first quarter of 2020, the computation of expected volatility is based only on the historical volatility of the Company’s common stock.

The following table summarizes stock option activity during the three months ended March 31, 2020:


	Shares	Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding, December 31, 2019	6,706,994	$	22.33	6.9
Granted	1,403,627	11.49
Exercised	(172,387)	0.94
Forfeited or expired	(293,295)	18.97
Outstanding, March 31, 2020	7,644,939	20.95		7.1	$	1,185
As of March 31, 2020:
Exercisable	4,358,640	23.05		5.6	1,184
Vested and expected to vest	7,306,954	21.04		7.0	1,185

The weighted-average grant-date fair value of options granted during the three months ended March 31, 2020 and 2019 was $7.12 and $14.65, respectively. The total intrinsic value of options exercised during the three months ended March 31, 2020 and 2019 was approximately $1.1 million and $1.6 million, respectively. The total cash received for options exercised during the three months ended March 31, 2020 and 2019 was approximately $0.2 million and $0.3 million, respectively. The total fair value of shares vested in the three months ended March 31, 2020 and 2019 was approximately $3.7 million and $3.1 million, respectively. As of March 31, 2020, the total unrecognized compensation expense related to unvested stock options, net of related forfeiture estimates, was approximately $33.0 million, which the Company expects to recognize over a weighted-average period of approximately 2.7 years.

Restricted Stock Units

During 2019, the Company awarded restricted stock units (RSUs) under the 2013 Plan to all employees with at least six months of service as of the date of grant except executive officers. Each RSU entitles the holder to receive one share of the Company's common stock when the RSU vests. The RSUs vest in two equal installments on the first and second anniversary of the grant date. Compensation expense is recognized on a straight-line basis. No RSUs were granted during the three months ended March 31, 2020.

The following table summarizes RSU activity during the three months ended March 31, 2020:


	Shares	Weighted-Average Grant Date Fair Value
Outstanding, December 31, 2019	452,500	$	15.32
Granted	—	—
Exercised	—	—
Forfeited or expired	(19,400)	15.32
Outstanding, March 31, 2020	433,100	15.32

At March 31, 2020, there was $4.3 million of total unrecognized compensation cost related to unvested RSUs, which the Company expects to recognize over a remaining weighted-average period of 1.4 years.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim consolidated financial statements of MacroGenics, Inc. (the Company) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiaries, MacroGenics UK Limited and MacroGenics Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2019 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2020.
Recently Adopted Accounting Standards	In June 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-13, which modifies the measurement of expected credit losses on certain financial instruments. In addition, for available-for-sale debt securities, the standard eliminates the concept of other-than-temporary impairment and requires the recognition of an allowance for credit losses rather than reductions in the amortized cost of the securities. The Company adopted ASU 2016-13 and all related ASU amendments on January 1, 2020, using a modified retrospective transition method, which requires a cumulative-effect adjustment, if any, to the opening balance of retained earnings to be recognized on the date of adoption with prior periods not restated. The Company evaluated its available-for-sale debt securities at January 1, 2020 and determined that no cumulative-effect adjustment was required. Adoption of the new standard did not have a material impact on the Company's consolidated financial statements. Under the new guidance, at each reporting date, entities must evaluate their individual available-for-sale debt securities that are in an unrealized loss position and determine whether the decline in fair value below the amortized cost basis results from a credit loss or other factors. The Company evaluates various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of the impairment. The amount of the decline related to credit losses is recorded as a credit loss expense in earnings with a corresponding allowance for credit losses and the amount of the decline not related to credit losses is recorded through other comprehensive income. See Note 4, Marketable Securities, for additional information. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (ASU 2018-15). This new standard requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in ASC 350-40, Accounting for Internal-Use Software, to determine which implementation costs to capitalize as assets and amortize over the term of the hosting arrangement or expense as incurred. The Company adopted ASU 2018-15 on January 1, 2020 on a prospective basis. Adoption of the new standard did not have a material impact on the Company's consolidated financial statements. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808)—Clarifying the interaction between Topic 808 and Topic 606 (ASU 2018-18). The amendments provide guidance on whether certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606. It also specifically (i) addresses when the participant should be considered a customer in the context of a unit of account, (ii) adds unit-of-account guidance in ASC 808 to align with guidance in ASC 606, and (iii) precludes presenting revenue from a collaborative arrangement together with revenue recognized under ASC 606 if the collaborative arrangement participant is not a customer. The Company adopted ASU 2018-15 on January 1, 2020 on a retrospective basis. Adoption of the new standard did not have a material impact on the Company's consolidated financial statements. The Company has evaluated all other ASUs issued through the date the consolidated financials were issued and believes that the adoption of these ASUs will not have a material impact on the Company's consolidated financial statements

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation Expense

The following stock-based compensation expense was recognized for the periods indicated (in thousands):


	Three Months Ended March 31,
	2020		2019
Research and development	$	2,434	$	1,814
General and administrative	2,057		1,985
Total stock-based compensation expense	$	4,491	$	3,799

Valuation Assumptions Using the Black-Scholes Option-Pricing Model


	Three Months Ended March 31,
	2020	2019
Expected dividend yield	0%	0%
Expected volatility	67.3% - 69.5%	73.7% - 74.4%
Risk-free interest rate	0.6% - 1.8%	2.3% - 2.6%
Expected term	6.25 years	6.25 years

Stock Option and Restricted Stock Unit Activity

The following table summarizes stock option activity during the three months ended March 31, 2020:


	Shares	Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding, December 31, 2019	6,706,994	$	22.33	6.9
Granted	1,403,627	11.49
Exercised	(172,387)	0.94
Forfeited or expired	(293,295)	18.97
Outstanding, March 31, 2020	7,644,939	20.95		7.1	$	1,185
As of March 31, 2020:
Exercisable	4,358,640	23.05		5.6	1,184
Vested and expected to vest	7,306,954	21.04		7.0	1,185

Schedule of RSU Activity

The following table summarizes RSU activity during the three months ended March 31, 2020:


	Shares	Weighted-Average Grant Date Fair Value
Outstanding, December 31, 2019	452,500	$	15.32
Granted	—	—
Exercised	—	—
Forfeited or expired	(19,400)	15.32
Outstanding, March 31, 2020	433,100	15.32

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Securities	$ 77,793	$ 89,284
Other assets	23,810	24,505
Fair Value Measurements, Recurring Basis
Assets:
Cash and cash equivalents	85,500	73,200
Total assets measured at fair value	163,271	162,506
Fair Value Measurements, Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	74,483	46,149
Fair Value Measurements, Recurring Basis \| Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	88,788	116,357
Fair Value Measurements, Recurring Basis \| Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	0	0
Fair Value Measurements, Recurring Basis \| Money market funds
Assets:
Cash and cash equivalents	74,483	46,149
Fair Value Measurements, Recurring Basis \| Money market funds \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	74,483	46,149
Fair Value Measurements, Recurring Basis \| Money market funds \| Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Fair Value Measurements, Recurring Basis \| Money market funds \| Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Fair Value Measurements, Recurring Basis \| Government-sponsored enterprises
Assets:
Securities	13,748	13,222
Fair Value Measurements, Recurring Basis \| Government-sponsored enterprises \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Securities	0	0
Fair Value Measurements, Recurring Basis \| Government-sponsored enterprises \| Significant Other Observable Inputs (Level 2)
Assets:
Securities	13,748	13,222
Fair Value Measurements, Recurring Basis \| Government-sponsored enterprises \| Significant Unobservable Inputs (Level 3)
Assets:
Securities	0	0
Fair Value Measurements, Recurring Basis \| Corporate debt securities
Assets:
Securities	75,040	103,135
Fair Value Measurements, Recurring Basis \| Corporate debt securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Securities	0	0
Fair Value Measurements, Recurring Basis \| Corporate debt securities \| Significant Other Observable Inputs (Level 2)
Assets:
Securities	75,040	103,135
Fair Value Measurements, Recurring Basis \| Corporate debt securities \| Significant Unobservable Inputs (Level 3)
Assets:
Securities	$ 0	$ 0

Marketable Securities (Details) - USD ($)	12 Months Ended
Marketable Securities (Details) - USD ($)	Dec. 31, 2019	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 89,268,000	$ 77,721,000
Gross Unrealized Gains	26,000	99,000
Gross Unrealized Losses	(10,000)	(27,000)
Fair Value	89,284,000	77,793,000
Allowance for credit loss related to available-for-sale debt securities		0
Losses related to other-than-temporary impairments of available-for-sale debt securities	0
Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	13,216,000	13,713,000
Gross Unrealized Gains	6,000	35,000
Gross Unrealized Losses	0	0
Fair Value	13,222,000	13,748,000
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	76,052,000	64,008,000
Gross Unrealized Gains	20,000	64,000
Gross Unrealized Losses	(10,000)	(27,000)
Fair Value	$ 76,062,000	$ 64,045,000

Collaboration and Other Agreements - Incyte Corporation (Details) - USD ($)	1 Months Ended	3 Months Ended			6 Months Ended
	Oct. 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2017	Jun. 30, 2019
Collaboration And Other Agreements [Line Items]
Revenues		$ 13,682,000	$ 9,662,000
Incyte Corporation \| Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment				$ 150,000,000.0
Potential development and regulatory milestone payments under agreement	$ 420,000,000.0
Potential commercial milestone payments under agreement	330,000,000.0
Development and regulatory milestones recognized					$ 15,000,000.0
Collaborative agreement transaction price	154,000,000.0
Variable consideration recognized	$ 4,000,000.0
Maximum \| Incyte Corporation \| Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	24.00%
Minimum \| Incyte Corporation \| Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	15.00%
Revenues From License Agreements \| Incyte Corporation \| Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Revenues	$ 150,000,000.0
Revenues From License Agreements \| Incyte Corporation \| Incyte MGA012 Agreement - Clinical activities
Collaboration And Other Agreements [Line Items]
Revenues		0	0
Revenues From License Agreements \| Incyte Corporation \| Incyte MGA012 Agreement - Services
Collaboration And Other Agreements [Line Items]
Revenues		$ 5,900,000	$ 4,000,000.0

Collaboration and Other Agreements - Zai Lab (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Collaboration And Other Agreements [Line Items]
Revenues		$ 13,682	$ 9,662
Deferred revenue, current		9,506		$ 10,700
Zai Lab Agreement \| Zai Labs
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment	$ 25,000
Non-refundable upfront payment, net of tax withholding	22,500
Nonrefundable payment tax withholding	$ 2,500
Potential development and regulatory milestone payments under agreement		140,000
Revenues		4,000	$ 4,000
Revenues, Net Of Tax Withholding		3,600
Revenues, Tax Withholding		400
Deferred revenue, current		5,000		$ 5,000
Zai Lab Clinical Supply Agreements \| Zai Labs
Collaboration And Other Agreements [Line Items]
Revenues		$ 1,000
Zai Lab Agreement, Margetuximab \| Zai Labs \| Maximum
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	20.00%
Zai Lab Agreement, TRIDENT molecule \| Zai Labs
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	10.00%

Collaboration and Other Agreements - I-Mab Biopharma (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jul. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jul. 09, 2019
Collaboration And Other Agreements [Line Items]
Revenues		$ 13,682	$ 9,662
Deferred revenue, current		9,506		$ 10,700
Deferred revenue, net of current portion		8,100		9,153
I-Mab \| I-Mab Biopharma Collaboration and License Agreement
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment	$ 15,000
Potential development and regulatory milestone payments under agreement					$ 135,000
Estimated variable consideration	$ 1,000
Revenues		1,100
Deferred revenue		12,400		13,500
Deferred revenue, current		4,300		4,400
Deferred revenue, net of current portion		$ 8,100		$ 9,100
I-Mab \| I-Mab Biopharma Collaboration and License Agreement \| Maximum
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)	20.00%

Collaboration and Other Agreements - Provention Bio, Inc. (Details)		3 Months Ended
	May 31, 2018 USD ($) performance_obligation $ / shares shares	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)
Collaboration And Other Agreements [Line Items]
Revenues		$ 13,682,000	$ 9,662,000
Fair Value		$ 77,793,000			$ 89,284,000
Provention
Collaboration And Other Agreements [Line Items]
Number of performance obligations \| performance_obligation	2
Collaborative agreement transaction price	$ 6,100,000
Number of shares available under warrants (in shares) \| shares	2,432,688
License Agreement \| Provention \| Provention PRV-3279
Collaboration And Other Agreements [Line Items]
Warrant to purchase shares of common stock, exercise price (in dollars per share) \| $ / shares	$ 2.50
Potential development and regulatory milestone payments under agreement	$ 65,000,000.0
Potential commercial milestone payments under agreement	$ 225,000,000.0
Asset Purchase Agreement \| Provention \| Provention PRV-031
Collaboration And Other Agreements [Line Items]
Warrant to purchase shares of common stock, exercise price (in dollars per share) \| $ / shares	$ 2.50
Potential development and regulatory milestone payments under agreement	$ 170,000,000.0
Potential commercial milestone payments under agreement	225,000,000.0
Potential milestone payments to third parties	$ 1,300,000
Revenues From License Agreements \| Provention
Collaboration And Other Agreements [Line Items]
Revenues				$ 6,100,000

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		7,644,939		6,706,994
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 20.95		$ 22.33
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 4,491	$ 3,799
2016 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)	800,000
Payroll deduction discount	10.00%
Purchase price of common stock percent of the fair market value	85.00%
Common stock purchased (in shares)		0
2003 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		376,079
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 2.96
Stock Incentive Plan 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)		11,896,613
Potential annual increase in shares reserved for future issuance (in shares)		1,960,168
Potential annual increase in shares reserved for future issuance as percentage of outstanding share		4.00%
Options outstanding (in shares)		7,268,860
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 21.88
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 2,434	1,814
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 2,057	$ 1,985

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Shares
Shares, Outstanding, Beginning Balance (in shares)	6,706,994
Shares, Granted (in shares)	1,403,627
Shares, Exercised (in shares)	(172,387)
Shares, Forfeited or expired (in shares)	(293,295)
Shares, Outstanding, Ending Balance (in shares)	7,644,939		6,706,994
Shares, Exercisable (in shares)	4,358,640
Shares, Vested and expected to vest (in shares)	7,306,954
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Outstanding, Beginning Balance (in dollars per share)	$ 22.33
Weighted- Average Exercise Price, Granted (in dollars per share)	11.49
Weighted- Average Exercise Price, Exercised (in dollars per share)	0.94
Weighted- Average Exercise Price, Forfeited or expired (in dollars per share)	(18.97)
Weighted- Average Exercise Price, Outstanding, Ending Balance (in dollars per share)	20.95		$ 22.33
Weighted- Average Exercise Price, Exercisable (in dollars per share)	23.05
Weighted- Average Exercise Price, Vested and expected to vest (in dollars per share)	$ 21.04
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted- Average Remaining Contractual Term, Outstanding	7 years 1 month 6 days		6 years 10 months 24 days
Weighted- Average Remaining Contractual Term, Exercisable	5 years 7 months 6 days
Weighted- Average Remaining Contractual Term, Vested and expected to vest	7 years
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 1,185
Aggregate Intrinsic Value, Exercisable	1,184
Aggregate Intrinsic Value, Vested and expected to vest	$ 1,185
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 7.12	$ 14.65
Intrinsic value of options exercised	$ 1,100	$ 1,600
Cash received for options exercised	200	300
Fair value of shares vested	3,700	$ 3,100
Unrecognized compensation expense related to non-vested stock-options, net of related forfeiture estimates	$ 33,000
Unrecognized compensation expense recognition period	2 years 8 months 12 days

Stock-based Compensation - Restricted Stock Unit Activity (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Weighted-Average Grant Date Fair Value
Unrecognized compensation expense recognition period	2 years 8 months 12 days
Restricted Stock Units
Shares
Beginning Balance (in shares)	452,500
Granted (in shares)	0
Exercised (in shares)	0
Forfeited or expired (in shares)	(19,400)
Ending Balance (in shares)	433,100
Weighted-Average Grant Date Fair Value
Beginning Balance (in dollars per share) \| $ / shares	$ 15.32
Granted (in dollars per share) \| $ / shares	0
Exercised (in dollars per share) \| $ / shares	0
Forfeited or expired (in dollars per share) \| $ / shares	15.32
Ending Balance (in dollars per share) \| $ / shares	$ 15.32
Awards granted in period (in shares)	0
Total unrecognized compensation cost \| $	$ 4.3
Unrecognized compensation expense recognition period	1 year 4 months 24 days

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2020
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity In February 2019, the Company completed a firm-commitment underwritten public offering, in which the Company sold 5,500,000 shares of its common stock at a price of $20.00 per share. Additionally, the underwriters of the offering exercised the full amount of their over-allotment option resulting in the sale of an additional 825,000 shares of the Company’s common stock at a price of $20.00 per share. The Company received net proceeds of approximately $118.7 million from this offering, net of underwriting discounts and commissions and other offering expenses. In December 2019, the Company entered into a sales agreement with an agent to sell, from time to time, shares of its common stock having an aggregate sales price of up to $50.0 million through an “at the market offering” (ATM Offering) as defined in Rule 415 under the Securities Act of 1933, as amended. The shares that may be sold under the sales agreement would be issued and sold pursuant to the Company's shelf registration statement on Form S-3 that was filed with the SEC on December 23, 2019. During the three months ended March 31, 2020, the Company did not sell any shares of common stock related to the ATM Offering.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesOn September 13, 2019, a securities class action complaint was filed in the U.S. District Court for the District of Maryland by Todd Hill naming the Company, its Chief Executive Officer, Dr. Koenig, and its Chief Financial Officer, Mr. Karrels, as defendants for allegedly making false and materially misleading statements regarding the Company’s SOPHIA trial. The complaint asserts a putative class period stemming from February 6, 2019 to June 3, 2019. On November 12, 2019, the Employees’ Retirement System of the City of Baton Rouge and Parish of East Baton Rouge sought appointment as lead plaintiff, which motion remains pending. The Company intends to vigorously defend against this action. However, the outcome of this legal proceeding is uncertain at this time and the Company cannot reasonably estimate a range of loss, if any. Accordingly, the Company has not accrued any liability associated with this action.

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended
	Dec. 31, 2019	Feb. 28, 2019	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Proceeds from issuance of common stock, net of offering costs			$ 0	$ 118,657
Follow-On Equity Offering
Class of Stock [Line Items]
Number of shares issued or sold (in shares)		5,500,000
Common stock purchase price (in dollars per share)		$ 20.00
Proceeds from issuance of common stock, net of offering costs		$ 118,700
Over-allotment option
Class of Stock [Line Items]
Number of shares issued or sold (in shares)		825,000
Common stock purchase price (in dollars per share)		$ 20.00
At the Market Offering
Class of Stock [Line Items]
Number of shares issued or sold (in shares)			0
Common stock maximum amount available for issuance	$ 50,000

Collaboration and Other Agreements - NIAID Contract (Details)		3 Months Ended		12 Months Ended
	Sep. 15, 2015 USD ($) Molecule	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)
Collaboration And Other Agreements [Line Items]
Revenues		$ 13,682,000	$ 9,662,000
NIAID
Collaboration And Other Agreements [Line Items]
Commercialization of molecules \| Molecule	2
Base period	$ 7,500,000
Additional development funding options under agreement	17,000,000.0
Total potential value	$ 24,500,000
Proceeds from additional development funding options under agreement				$ 10,800,000
Revenues From Grants \| NIAID
Collaboration And Other Agreements [Line Items]
Revenues		$ 700,000	$ 200,000

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares outstanding (in shares)	49,131,150	48,958,763