MacroGenics (MGNX) 10-Q 8 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Nov. 03, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Entity Registrant Name	MACROGENICS INC
Entity Central Index Key	1,125,345
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		36,822,710

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 90,884	$ 84,098
Marketable securities	112,763	192,898
Accounts receivable	2,194	2,764
Prepaid expenses	3,261	3,483
Other current assets	364	704
Total current assets	209,466	283,947
Property and equipment, net	30,838	17,961
Marketable securities, non-current	0	7,986
Other assets	1,541	1,369
Total assets	241,845	311,263
Current liabilities:
Accounts payable	1,680	3,995
Accrued expenses	25,501	16,134
Deferred revenue	3,202	4,261
Deferred rent	1,165	1,319
Lease exit liability	715	1,593
Other liabilities	175	0
Total current liabilities	32,438	27,302
Deferred revenue, net of current portion	8,438	10,045
Deferred rent, net of current portion	11,504	4,867
Lease exit liability, net of current portion	0	298
Total liabilities	52,380	42,512
Stockholders' equity:
Common stock, $0.01 par value – 125,000,000 shares authorized, 36,807,112 and 34,870,607 shares outstanding at September 30, 2017 and December 31, 2016, respectively	368	349
Additional paid-in capital	607,191	561,198
Accumulated deficit	(418,067)	(292,714)
Accumulated other comprehensive loss	(27)	(82)
Total stockholders' equity	189,465	268,751
Total liabilities and stockholders' equity	$ 241,845	$ 311,263

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
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)	36,807,112	34,870,607

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Revenue from collaborative agreements	$ 1,076	$ 2,014	$ 3,435	$ 82,404
Revenue from government agreements	587	1,241	1,948	4,370
Total revenues	1,663	3,255	5,383	86,774
Costs and expenses:
Research and development	40,984	30,296	108,246	90,982
General and administrative	8,403	7,224	24,249	20,596
Total costs and expenses	49,387	37,520	132,495	111,578
Loss from operations	(47,724)	(34,265)	(127,112)	(24,804)
Other income	681	419	1,759	1,059
Net loss	(47,043)	(33,846)	(125,353)	(23,745)
Other comprehensive loss:
Unrealized gain (loss) on investments	56	(41)	55	23
Comprehensive loss	$ (46,987)	$ (33,887)	$ (125,298)	$ (23,722)
Basic and diluted net loss per common share (in usd per share)	$ (1.28)	$ (0.97)	$ (3.50)	$ (0.69)
Basic and diluted weighted average common shares outstanding (in shares)	36,779,305	34,766,440	35,847,449	34,629,330

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (125,353)	$ (23,745)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	5,886	5,634
Stock-based compensation	11,064	9,126
Changes in operating assets and liabilities:
Accounts receivable	570	(1,784)
Prepaid expenses	222	495
Other assets	168	(599)
Accounts payable and other liabilities	(2,138)	(133)
Accrued expenses	9,501	3,895
Lease exit liability	(1,176)	(2,473)
Deferred revenue	(2,666)	(4,920)
Deferred rent	6,482	(846)
Net cash used in operating activities	(97,440)	(15,350)
Cash flows from investing activities
Purchases of marketable securities	(89,124)	(269,697)
Proceeds from sale and maturities of marketable securities	177,006	207,733
Purchases of property and equipment	(18,645)	(10,319)
Net cash provided by (used in) investing activities	69,237	(72,283)
Cash flows from financing activities
Proceeds from issuance of common stock, net of offering costs	34,294	0
Proceeds from stock option exercises and ESPP purchases	695	1,362
Net cash provided by financing activities	34,989	1,362
Net change in cash and cash equivalents	6,786	(86,271)
Cash and cash equivalents at beginning of period	84,098	196,172
Cash and cash equivalents at end of period	$ 90,884	$ 109,901

Basis of Presentation and Recen

Basis of Presentation and Recently Issued Accounting Standards	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Recently Issued Accounting Standards	Basis of Presentation and Recently Issued Accounting Standards 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 subsidiary, MacroGenics UK 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 2016 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 28, 2017. There have been no material changes to the significant accounting policies previously disclosed in the Company's 2016 Annual Report on Form 10-K other than as disclosed in the Recently Issued Accounting Standards section below. Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). ASU 2014-09 will eliminate transaction- and industry-specific revenue recognition guidance under current GAAP and replace it with a principle-based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein, with early adoption permitted for interim and annual reporting periods beginning after December 15, 2016. ASU 2014-09 may be adopted either retrospectively or on a modified retrospective basis whereby ASU 2014-09 would be applied to new contracts and existing contracts with remaining performance obligations as of the effective date, with a cumulative catch-up adjustment recorded to beginning retained earnings at the effective date for existing contracts with remaining performance obligations. In 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations , ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , and ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients to provide supplemental adoption guidance and clarification to ASU 2014-09. The effective date for these new standards is the same as the effective date and transition requirements for ASU 2014-09. The Company plans to adopt the new standard effective January 1, 2018 using the modified retrospective method with the cumulative effect of initially applying the new standard recognized in retained earnings at the date of initial adoption. Management has performed an initial review of each of the Company's collaboration and license agreements and assessed the potential effects of the standard on the Company's consolidated financial statements, accounting policies, and internal control over financial reporting. The Company does not anticipate that the adoption of the new revenue recognition standard will have a material impact on its contract revenues generated by its collaborative research and license agreements. In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02) that provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. ASU 2016-02 requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. ASU 2016-02 includes a short-term lease exception for leases with a term of 12 months or less, in which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases, using classification criteria that are substantially similar to the previous guidance. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with earlier application permitted. Entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. The Company is currently evaluating the effect of the standard on its consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). This amendment addresses several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within that year. The Company adopted ASU 2016-09 effective January 1, 2017 and has elected to continue to estimate the number of stock-based awards expected to vest, as permitted by ASU 2016-09, rather than electing to account for forfeitures as they occur. The adoption of this standard did not have a material impact on the Company's financial statements or related disclosures.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	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 FASB 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 September 30, 2017 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 $ 72,744 $ 72,744 $ — $ — U.S. Treasury securities 12,759 — 12,759 — Government-sponsored enterprises 22,983 — 22,983 — Corporate debt securities 77,021 — 77,021 — Total assets measured at fair value (a) $ 185,507 $ 72,744 $ 112,763 $ — (a) Total assets measured at fair value at September 30, 2017 includes approximately $72.7 million reported in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2016 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 $ 46,781 $ 46,781 $ — $ — U.S. Treasury securities 8,826 — 8,826 — Government-sponsored enterprises 29,759 — 29,759 — Corporate debt securities 166,300 — 166,300 — Total assets measured at fair value (a) $ 251,666 $ 46,781 $ 204,885 $ — (a) Total assets measured at fair value at December 31, 2016 includes approximately $50.8 million reported in cash and cash equivalents on the 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 Level 1 and Level 2 investments during the periods presented.

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities Available-for-sale marketable securities as of September 30, 2017 and December 31, 2016 were as follows (in thousands): September 30, 2017 Amortized Gross Gross Fair U.S. Treasury securities $ 12,770 $ — $ (11 ) $ 12,759 Government-sponsored enterprises 22,995 — (12 ) 22,983 Corporate debt securities 77,025 12 (16 ) 77,021 Total $ 112,790 $ 12 $ (39 ) $ 112,763 December 31, 2016 Amortized Gross Gross Fair U.S. Treasury securities $ 4,826 $ — $ (1 ) $ 4,825 Government-sponsored enterprises 29,764 5 (10 ) 29,759 Corporate debt securities 166,376 51 (127 ) 166,300 Total $ 200,966 $ 56 $ (138 ) $ 200,884 All available-for-sale marketable securities held as of September 30, 2017 had contractual maturities of less than one year. All of the Company's available-for-sale marketable securities in an unrealized loss position as of September 30, 2017 and December 31, 2016 were in a loss position for less than twelve months. There were no unrealized losses at September 30, 2017 or December 31, 2016 that the Company determined to be other-than-temporary.

Lease Exit Liability

Lease Exit Liability	9 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Lease Exit Liability	Lease Exit Liability In 2008, the Company acquired Raven Biotechnologies, Inc. (Raven), a private South San Francisco-based company focused on the development of monoclonal antibody therapeutics for treating cancer. The Company undertook restructuring activities related to the acquisition of Raven. In connection with these restructuring activities, as part of the cost of acquisition, the Company established a restructuring liability attributed to an existing operating lease. During the year ended December 31, 2016, the Company entered into an agreement to sublease a portion of the space subject to this operating lease. The Company will receive approximately $1.3 million in sublease payments over its term, which ends at the same time as the original lease in February 2018. No sublease income was contemplated when the restructuring liability was recorded in 2008; therefore, the Company adjusted the liability to reflect the future sublease income during the year ended December 31, 2016 and recorded an offset to research and development expenses of approximately $1.3 million in the same period. Changes in the lease exit liability are as follows (in thousands): Accrual balance at December 31, 2016 $ 1,891 Principal payments (1,176 ) Accrual balance at September 30, 2017 $ 715

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity On April 26, 2017, the Company entered into a definitive agreement with an institutional healthcare investor to purchase 1,100,000 shares of its common stock at a purchase price of $21.50 per share in a registered direct offering. Proceeds to the Company, before deducting estimated offering expenses, were $23.7 million . The shares were offered pursuant to the Company’s effective shelf registration on Form S-3 that was filed with the SEC on November 2, 2016 . On May 3, 2017, 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 $75.0 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 November 2, 2016. During the three and nine months ended September 30, 2017, the Company sold 62,342 and 599,284 shares of common stock under the sales agreement, respectively, resulting in net proceeds of $1.1 million and $10.8 million , respectively, related to the ATM Offering.

Collaboration and Other Agreeme

Collaboration and Other Agreements	9 Months Ended
	Sep. 30, 2017
Collaboration and License Agreements [Abstract]
Collaboration and Other Agreements	Collaboration and Other Agreements Janssen Biotech, Inc. In December 2014 , the Company entered into a collaboration and license agreement with Janssen Biotech, Inc. (Janssen) for the development and commercialization of MGD011 (also known as duvortuxizumab) (MGD011 Agreement). The Company contemporaneously entered into an agreement with Johnson & Johnson Innovation - JJDC, Inc. (JJDC) under which JJDC agreed to purchase 1,923,077 new shares of the Company's common stock for proceeds of $75.0 million . Upon closing the transaction in January 2015, the Company received a $50.0 million upfront payment from Janssen as well as the $75.0 million investment in the Company's common stock. Under the MGD011 Agreement, the Company granted an exclusive license to Janssen to develop and commercialize duvortuxizumab. Following the Company's submission of the Investigational New Drug (IND) application, Janssen became fully responsible for the development and commercialization of duvortuxizumab. In August 2017, Janssen notified the Company that they were terminating the MGD011 Agreement. In May 2016 , the Company entered into a separate collaboration and license agreement with Janssen, a related party through ownership of the Company's common stock, for the development and commercialization of MGD015 (also known as JNJ-9383), a product candidate that incorporates the Company's proprietary DART technology to simultaneously target CD3 and an undisclosed tumor target for the potential treatment of various hematological malignancies and solid tumors (MGD015 Agreement). The transaction closed in June 2016, and the Company received the $75.0 million upfront payment from Janssen in July 2016. Under the MGD015 Agreement, the Company granted an exclusive license to Janssen to develop and commercialize MGD015. Janssen will complete the IND-enabling activities and will be fully responsible for the future clinical development and commercialization of MGD015. Assuming successful development and commercialization, the agreement entitles the Company to receive up to $100.0 million in development milestone payments, $265.0 million in regulatory milestone payments and $300.0 million in sales milestone payments. The Company determined that each potential future clinical and regulatory milestone is substantive. Although the sales milestones are not considered substantive, they will be recognized upon achievement of the milestone (assuming all other revenue recognition criteria have been met) because there are no undelivered elements that would preclude revenue recognition at that time. The Company may elect to fund a portion of late-stage clinical development in exchange for a profit share with Janssen in the U.S. and Canada. If commercialized, the Company would be eligible to receive low double-digit royalties on any global net sales and has the option to co-promote the molecule with Janssen in the United States. The Company evaluated the MGD015 Agreement and determined that it is a revenue arrangement with multiple deliverables, or performance obligations. The Company's substantive performance obligations under the MGD015 Agreement include the delivery of an exclusive license and research and development services during the preclinical research period. The Company evaluated the MGD015 Agreement and determined that the license and preclinical research and development activities each represented separate deliverables and were accounted for as two separate units of accounting. The Company concluded that the license had standalone value to Janssen and was separable from the research and development services because the license was sublicensable, there were no restrictions as to Janssen's use of the license and Janssen or other third parties have significant research capabilities in this field. Thus, the total arrangement consideration for these two deliverables was allocated using the best estimate of relative selling price method to each deliverable. The best estimate of selling price for the exclusive license was determined using information from the previous collaboration and license agreement with Janssen as well as other third party collaboration and license agreements, which are Level 2 fair value measurements. The best estimate of selling price for the research and development services was determined using other similar research and development arrangements, which are also Level 2 fair value measurements. The Company recognized $0.2 million and $0.5 million of revenue under the MGD015 Agreement during the three and nine months ended September 30, 2017 , respectively. No revenue was recognized under the MGD015 Agreement during the three months ended September 30, 2016 . $75.0 million of revenue was recognized under the MGD015 Agreement during the nine months ended September 30, 2016 . Les Laboratoires Servier In September 2012 , the Company entered into a right-to-develop collaboration agreement with Les Laboratoires Servier and Institut de Recherches Servier (collectively, Servier) and granted it options to obtain three separate exclusive licenses to develop and commercialize DART molecules, consisting of those designated by the Company as flotetuzumab (also known as MGD006 or S80880) and MGD007, as well as a third DART molecule, in all countries other than the United States, Canada, Mexico, Japan, South Korea and India. During 2014, Servier exercised its exclusive option to develop and commercialize flotetuzumab, and during 2016 Servier notified the Company that it did not intend to exercise the option for the third DART molecule. Servier retains the option to obtain a license for MGD007. Upon execution of the agreement, Servier made a nonrefundable payment of $20.0 million to the Company. In addition, the Company will be eligible to receive up to $40.0 million in license fees, $63.0 million in clinical milestone payments, $188.0 million in regulatory milestone payments and $420.0 million in sales milestone payments if Servier exercises the remaining available options and successfully develops, obtains regulatory approval for, and commercializes a product under each license. In addition to these milestones, the Company and Servier will share Phase 2 and Phase 3 development costs. The Company has determined that each potential future clinical and regulatory milestone is substantive. Although sales milestones are not considered substantive, they are still recognized upon achievement of the milestone (assuming all other revenue recognition criteria have been met) because there are no undelivered elements that would preclude revenue recognition at that time. Under this agreement, Servier would be obligated to pay the Company from low double-digit to mid-teen royalties on net product sales in its territories. The Company evaluated the research collaboration agreement with Servier and determined that it is a revenue arrangement with multiple deliverables, or performance obligations. The Company concluded that each option is substantive and that the license fees for each option are not deliverables at the inception of the arrangement and were not issued with a substantial discount. The Company's substantive performance obligations under this research collaboration include an exclusivity clause to its technology, technical, scientific and intellectual property support to the research plan and participation on an executive committee and a research and development committee. The Company determined that the performance obligations with respect to the preclinical development represent a single unit of accounting, since the license does not have stand-alone value to Servier without the Company's technical expertise and committee participation. As such, the initial upfront license payment was deferred and initially recognized ratably over a 29 -month period, which represented the expected development period. During 2014, the Company and Servier further refined the research plan related to the three DART molecules and as such, the development period was extended. Based on this revised development period, the Company prospectively adjusted its period of recognition of the upfront payment to a 75 -month period. The impact of this change in accounting estimate reduced revenue that would have been recognized in 2014 by $3.7 million . As a result of Servier exercising its option in 2014, the Company received a $15.0 million payment from Servier for its license to develop and commercialize flotetuzumab in its territories. Upon exercise of the option, the Company evaluated its performance obligations with respect to the license for flotetuzumab. The Company's substantive performance obligations under this research collaboration include an exclusive license to its technology, technical, scientific and intellectual property support to the research plan and participation on an executive committee and a research and development committee. The Company determined that the performance obligations with respect to the clinical development represent a single unit of accounting, since the license does not have stand-alone value to Servier without the Company's technical expertise and committee participation. As such, the $15.0 million license fee was deferred and was being recognized ratably over a period of 82 months, which represented the expected development period for flotetuzumab. During the three months ended June 30, 2017, the Company and Servier determined that the expected development period should be extended to 124 months. The impact of this change in accounting estimate reduced revenue that would have been recognized in 2017 by $0.8 million . In accordance with the agreement, the Company and Servier will share costs incurred to develop flotetuzumab. Reimbursement of research and development expenses received in connection with this collaborative cost-sharing agreement is recorded as a reduction to research and development expense. During the three months ended September 30, 2017 and 2016, the Company recorded approximately $0.6 million and $1.0 million , respectively, as an offset to research and development costs under this collaboration agreement. During the nine months ended September 30, 2017 and 2016 , the Company recorded approximately $1.5 million and $2.1 million , respectively, as an offset to research and development costs under this collaboration agreement. The Company recognized revenue under this agreement of $0.6 million and $0.8 million during the three months ended September 30, 2017 and 2016 , respectively. The Company recognized revenue under this agreement of $2.0 million and $2.5 million during the nine months ended September 30, 2017 and 2016 , respectively. At September 30, 2017 , $9.1 million of revenue was deferred under this agreement, $2.3 million of which was current and $6.8 million of which was non-current. At December 31, 2016 , $11.1 million of revenue was deferred under this agreement, $3.3 million of which was current and $7.8 million of which was non-current. NIAID Contract The Company entered into a contract with the National Institute of Allergy and Infectious Diseases (NIAID), effective as of September 15, 2015, to perform product development and to advance up to two DART molecules, including MGD014. Under this 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. This contract includes a base period of $7.5 million to support development of MGD014 through IND application submission with the FDA, 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 September 14, 2022 . During the three months ended September 30, 2017, NIAID exercised the first option in the amount of $10.8 million . The Company recognized $0.4 million and $1.2 million in revenue under this contract during the three months ended September 30, 2017 and 2016 , respectively. The Company recognized $1.5 million and $4.3 million in revenue under this contract during the nine months ended September 30, 2017 and 2016 , respectively.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	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, 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 nine months ended September 30, 2017 , employees purchased 19,351 shares of common stock under the 2016 ESPP for net proceeds to the Company of approximately $0.3 million . 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. The 2003 Plan originally allowed for the grant of awards in respect of an aggregate of 2,051,644 shares of the Company's common stock. Between 2006 and 2012, the maximum number of shares of common stock authorized to be issued by the Company under the 2003 Plan was increased to 4,336,730 . Stock options granted under the 2003 Plan may be either incentive stock options as defined by the Internal Revenue Code (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 Company's 2013 Stock Incentive Plan (2013 Plan), up to a specified number of shares. As of September 30, 2017 there were options to purchase an aggregate of 989,239 shares of common stock outstanding at a weighted average exercise price of $1.89 per share under the 2003 Plan. Under the provisions of the 2013 Plan, the number of shares of common stock reserved for issuance 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 Board of Directors. During the nine months ended September 30, 2017 , the maximum number of shares of common stock authorized to be issued by the Company under the 2013 Plan was increased to 6,769,888 . As of September 30, 2017 , there were options to purchase an aggregate of 3,544,555 shares of common stock outstanding at a weighted average exercise price of $24.69 per share under the 2013 Plan. The following table shows stock-based compensation expense for stock options, RSUs and ESPP (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ 2,006 $ 1,403 $ 5,512 $ 4,243 General and administrative 1,995 1,600 5,552 4,883 Total stock-based compensation expense $ 4,001 $ 3,003 $ 11,064 $ 9,126 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: Nine Months Ended September 30, 2017 2016 Expected dividend yield 0% 0% Expected volatility 66.7% - 68.3% 63.7% - 67.7% Risk-free interest rate 1.9% - 2.3% 1.2% - 2.1% Expected term 6.25 years 6.25 years The following table summarizes stock option and restricted stock unit (RSU) activity during the nine months ended September 30, 2017 : Shares Weighted- Weighted-Average Aggregate Outstanding, December 31, 2016 3,838,060 $ 18.93 7.0 Granted 1,219,725 20.09 Exercised (219,732 ) 2.02 Forfeited or expired (304,259 ) 24.13 Outstanding, September 30, 2017 4,533,794 19.71 7.2 $ 18,050 As of September 30, 2017: Exercisable 2,704,057 16.86 6.2 17,254 Vested and expected to vest 4,352,976 19.48 7.2 17,993 The weighted-average grant-date fair value of options granted during the nine months ended September 30, 2017 was $12.56 . The total intrinsic value of options exercised during the nine months ended September 30, 2017 was approximately $3.7 million , and the total cash received for options exercised was approximately $0.4 million . The total fair value of shares vested in the nine months ended September 30, 2017 was approximately $10.7 million . As of September 30, 2017 , the total unrecognized compensation expense related to non-vested stock options, net of related forfeiture estimates, was approximately $23.7 million , which the Company expects to recognize over a weighted-average period of approximately 2.5 years.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company leases manufacturing, office and laboratory space in Rockville, Maryland under five leases that have terms that expire between 2018 and 2027 unless renewed. During the three months ended September 30, 2017, the Company entered into an agreement to sublease a portion of the space it leases. Under the terms of the sublease, the Company will receive a total of $2.4 million over the 30 month term. The Rockville leases include a lease executed in July 2015 for space that the Company uses as its headquarters with office and laboratory space and manufacturing space currently under construction. Under the terms of the lease, which commenced on January 1, 2016 , the Company received an assignment fee from the former tenant and a tenant improvement allowance from the landlord totaling $5.1 million . In July 2017, the Company executed a lease amendment for its headquarters building which extends the term of the lease to August 2027, restructures the rent due under the lease, and provides for an additional tenant improvement allowance from the landlord of $7.5 million , which was received during the third quarter. The assignment fee and tenant improvement allowances have been recorded as deferred rent and are being recognized over the new lease term. The Company also leases office and laboratory space in South San Francisco under a lease that expires on February 28, 2018 . During the year ended December 31, 2016 , the Company entered into a sublease agreement for a portion of the South San Francisco space (see Note 4). As of September 30, 2017 , future payments to be received by the Company under this sublease total approximately $0.3 million . In April 2017 , the Company entered into a 72 -month lease commencing in December 2017 for office and laboratory space which will replace our current South San Francisco location. All of the leases contain rent escalation clauses and certain leases contain rent abatements. For financial reporting purposes, rent expense is charged to operations on a straight-line basis over the term of the lease. Future minimum lease payments under noncancelable operating leases as of September 30, 2017 are as follows (in thousands): Year Ended December 31, 2017 $ 6,985 2018 6,574 2019 6,342 2020 4,775 2021 4,743 Thereafter 23,370 $ 52,789 Contingencies From time to time, the Company may be subject to various litigation and related matters arising in the ordinary course of business. The Company does not believe it is currently subject to any material matters where there is at least a reasonable possibility that a material loss may be incurred.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic loss per common share is determined by dividing loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted loss per share is computed by dividing the loss attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period. The treasury stock method is used to determine the dilutive effect of the Company's stock option grants. 4,533,794 stock options (common stock equivalents) were excluded from the calculation of diluted loss per share for the three and nine months ended September 30, 2017 because their inclusion would have been anti-dilutive. 3,856,652 stock options were excluded from the calculation of diluted loss per share for the three and nine months ended September 30, 2016 because their inclusion would have been anti-dilutive. Basic and diluted loss per common share is computed as follows (in thousands except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Numerator: Net loss used for calculation of basic and diluted EPS $ (47,043 ) $ (33,846 ) $ (125,353 ) $ (23,745 ) Denominator: Weighted average shares outstanding, basic 36,779,305 34,766,440 35,847,449 34,629,330 Effect of dilutive securities: Stock options and restricted stock units — — — — Weighted average shares outstanding, diluted 36,779,305 34,766,440 35,847,449 34,629,330 Net loss per share, basic and diluted $ (1.28 ) $ (0.97 ) $ (3.50 ) $ (0.69 )

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	Subsequent Events In October 2017, the Company entered into a global collaboration and license agreement with Incyte Corporation (Incyte) for the development and commercialization of MGA012, an investigational anti-PD-1 monoclonal antibody. Incyte has obtained exclusive worldwide rights for the development and commercialization of MGA012 in all indications, while the Company retains the right to develop its pipeline assets in combination with MGA012. As part of the MGA012 collaboration with Incyte, the Company retains the right to manufacture a portion of both companies' global clinical and commercial supply needs of MGA012. Upon closing, the Company will receive a $150.0 million upfront payment from Incyte. Assuming successful development and commercialization, the Company could receive up to $750.0 million in clinical, regulatory and commercialization milestone payments. If commercialized, the Company would be eligible to receive tiered royalties of 15% to 24% on global net sales of MGA012 by Incyte. The transaction is expected to close in the fourth quarter of 2017, subject to the early termination or expiration of any applicable waiting periods under Hart-Scott-Rodino Antitrust Improvements Act of 1976 and customary closing conditions.

Basis of Presentation and Rec16

Basis of Presentation and Recently Issued Accounting Standards (Policies)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [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 subsidiary, MacroGenics UK 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 2016 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 28, 2017. There have been no material changes to the significant accounting policies previously disclosed in the Company's 2016 Annual Report on Form 10-K other than as disclosed in the Recently Issued Accounting Standards section below.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). ASU 2014-09 will eliminate transaction- and industry-specific revenue recognition guidance under current GAAP and replace it with a principle-based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein, with early adoption permitted for interim and annual reporting periods beginning after December 15, 2016. ASU 2014-09 may be adopted either retrospectively or on a modified retrospective basis whereby ASU 2014-09 would be applied to new contracts and existing contracts with remaining performance obligations as of the effective date, with a cumulative catch-up adjustment recorded to beginning retained earnings at the effective date for existing contracts with remaining performance obligations. In 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations , ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , and ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients to provide supplemental adoption guidance and clarification to ASU 2014-09. The effective date for these new standards is the same as the effective date and transition requirements for ASU 2014-09. The Company plans to adopt the new standard effective January 1, 2018 using the modified retrospective method with the cumulative effect of initially applying the new standard recognized in retained earnings at the date of initial adoption. Management has performed an initial review of each of the Company's collaboration and license agreements and assessed the potential effects of the standard on the Company's consolidated financial statements, accounting policies, and internal control over financial reporting. The Company does not anticipate that the adoption of the new revenue recognition standard will have a material impact on its contract revenues generated by its collaborative research and license agreements. In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02) that provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. ASU 2016-02 requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. ASU 2016-02 includes a short-term lease exception for leases with a term of 12 months or less, in which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases, using classification criteria that are substantially similar to the previous guidance. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with earlier application permitted. Entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. The Company is currently evaluating the effect of the standard on its consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). This amendment addresses several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within that year. The Company adopted ASU 2016-09 effective January 1, 2017 and has elected to continue to estimate the number of stock-based awards expected to vest, as permitted by ASU 2016-09, rather than electing to account for forfeitures as they occur. The adoption of this standard did not have a material impact on the Company's financial statements or related disclosures.

Fair Value of Financial Instr17

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Financial Assets Measured at Fair Value on a Recurring Basis	Financial assets measured at fair value on a recurring basis were as follows (in thousands): Fair Value Measurements at September 30, 2017 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 $ 72,744 $ 72,744 $ — $ — U.S. Treasury securities 12,759 — 12,759 — Government-sponsored enterprises 22,983 — 22,983 — Corporate debt securities 77,021 — 77,021 — Total assets measured at fair value (a) $ 185,507 $ 72,744 $ 112,763 $ — (a) Total assets measured at fair value at September 30, 2017 includes approximately $72.7 million reported in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2016 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 $ 46,781 $ 46,781 $ — $ — U.S. Treasury securities 8,826 — 8,826 — Government-sponsored enterprises 29,759 — 29,759 — Corporate debt securities 166,300 — 166,300 — Total assets measured at fair value (a) $ 251,666 $ 46,781 $ 204,885 $ — (a) Total assets measured at fair value at December 31, 2016 includes approximately $50.8 million reported in cash and cash equivalents on the balance sheet.

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Marketable Securities	Available-for-sale marketable securities as of September 30, 2017 and December 31, 2016 were as follows (in thousands): September 30, 2017 Amortized Gross Gross Fair U.S. Treasury securities $ 12,770 $ — $ (11 ) $ 12,759 Government-sponsored enterprises 22,995 — (12 ) 22,983 Corporate debt securities 77,025 12 (16 ) 77,021 Total $ 112,790 $ 12 $ (39 ) $ 112,763 December 31, 2016 Amortized Gross Gross Fair U.S. Treasury securities $ 4,826 $ — $ (1 ) $ 4,825 Government-sponsored enterprises 29,764 5 (10 ) 29,759 Corporate debt securities 166,376 51 (127 ) 166,300 Total $ 200,966 $ 56 $ (138 ) $ 200,884

Lease Exit Liability (Tables)

Lease Exit Liability (Tables)	9 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Changes in Lease Exit Liability	Changes in the lease exit liability are as follows (in thousands): Accrual balance at December 31, 2016 $ 1,891 Principal payments (1,176 ) Accrual balance at September 30, 2017 $ 715

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense	The following table shows stock-based compensation expense for stock options, RSUs and ESPP (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ 2,006 $ 1,403 $ 5,512 $ 4,243 General and administrative 1,995 1,600 5,552 4,883 Total stock-based compensation expense $ 4,001 $ 3,003 $ 11,064 $ 9,126
Valuation Assumptions Using the Black-Scholes Option-Pricing Model	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: Nine Months Ended September 30, 2017 2016 Expected dividend yield 0% 0% Expected volatility 66.7% - 68.3% 63.7% - 67.7% Risk-free interest rate 1.9% - 2.3% 1.2% - 2.1% Expected term 6.25 years 6.25 years
Stock Option and Restricted Stock Unit Activity	The following table summarizes stock option and restricted stock unit (RSU) activity during the nine months ended September 30, 2017 : Shares Weighted- Weighted-Average Aggregate Outstanding, December 31, 2016 3,838,060 $ 18.93 7.0 Granted 1,219,725 20.09 Exercised (219,732 ) 2.02 Forfeited or expired (304,259 ) 24.13 Outstanding, September 30, 2017 4,533,794 19.71 7.2 $ 18,050 As of September 30, 2017: Exercisable 2,704,057 16.86 6.2 17,254 Vested and expected to vest 4,352,976 19.48 7.2 17,993

Commitments and Contingencies

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Minimum Future Lease Payments	Future minimum lease payments under noncancelable operating leases as of September 30, 2017 are as follows (in thousands): Year Ended December 31, 2017 $ 6,985 2018 6,574 2019 6,342 2020 4,775 2021 4,743 Thereafter 23,370 $ 52,789

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Basic and Diluted Loss Per Common Share Computation	Basic and diluted loss per common share is computed as follows (in thousands except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Numerator: Net loss used for calculation of basic and diluted EPS $ (47,043 ) $ (33,846 ) $ (125,353 ) $ (23,745 ) Denominator: Weighted average shares outstanding, basic 36,779,305 34,766,440 35,847,449 34,629,330 Effect of dilutive securities: Stock options and restricted stock units — — — — Weighted average shares outstanding, diluted 36,779,305 34,766,440 35,847,449 34,629,330 Net loss per share, basic and diluted $ (1.28 ) $ (0.97 ) $ (3.50 ) $ (0.69 )

Fair Value of Financial Instr23

Fair Value of Financial Instruments (Details) - Fair Value Measurements, Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 72,700	$ 50,800
Total assets measured at fair value	185,507	251,666
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	72,744	46,781
Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	112,763	204,885
Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	0	0
Money market funds
Assets:
Cash and cash equivalents	72,744	46,781
Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	72,744	46,781
Money market funds | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Money market funds | Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
U.S. Treasury securities
Assets:
Available-for-sale securities	12,759	8,826
U.S. Treasury securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Available-for-sale securities	0	0
U.S. Treasury securities | Significant Other Observable Inputs (Level 2)
Assets:
Available-for-sale securities	12,759	8,826
U.S. Treasury securities | Significant Unobservable Inputs (Level 3)
Assets:
Available-for-sale securities	0	0
Government-sponsored enterprises
Assets:
Available-for-sale securities	22,983	29,759
Government-sponsored enterprises | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Available-for-sale securities	0	0
Government-sponsored enterprises | Significant Other Observable Inputs (Level 2)
Assets:
Available-for-sale securities	22,983	29,759
Government-sponsored enterprises | Significant Unobservable Inputs (Level 3)
Assets:
Available-for-sale securities	0	0
Corporate debt securities
Assets:
Available-for-sale securities	77,021	166,300
Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Available-for-sale securities	0	0
Corporate debt securities | Significant Other Observable Inputs (Level 2)
Assets:
Available-for-sale securities	77,021	166,300
Corporate debt securities | Significant Unobservable Inputs (Level 3)
Assets:
Available-for-sale securities	$ 0	$ 0

Marketable Securities (Details)

Marketable Securities (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 112,790,000	$ 200,966,000
Gross Unrealized Gains	12,000	56,000
Gross Unrealized Losses	(39,000)	(138,000)
Fair Value	112,763,000	200,884,000
Other-than-temporary unrealized losses	0	0
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,770,000	4,826,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11,000)	(1,000)
Fair Value	12,759,000	4,825,000
Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	22,995,000	29,764,000
Gross Unrealized Gains	0	5,000
Gross Unrealized Losses	(12,000)	(10,000)
Fair Value	22,983,000	29,759,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	77,025,000	166,376,000
Gross Unrealized Gains	12,000	51,000
Gross Unrealized Losses	(16,000)	(127,000)
Fair Value	$ 77,021,000	$ 166,300,000

Lease Exit Liability - Narrativ

Lease Exit Liability - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2017	Jul. 06, 2017	May 10, 2016
Restructuring Cost and Reserve [Line Items]
Future sublease payments to be received		$ 0.3	$ 2.4
Reduction in research and development expense	$ 1.3
Raven Biotechnologies Inc
Restructuring Cost and Reserve [Line Items]
Future sublease payments to be received				$ 1.3

Lease Exit Liability - Changes

Lease Exit Liability - Changes in Lease Exit Liability (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Restructuring Reserve [Roll Forward]
Accrual beginning balance	$ 1,891
Principal payments	(1,176)
Accrual ending balance	$ 715

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	May 03, 2017	Apr. 26, 2017	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock, net of offering costs				$ 34,294	$ 0
Registered Direct Offering
Subsidiary, Sale of Stock [Line Items]
Shares of common stock purchased (in shares)		1,100,000
Common stock purchase price (in dollars per share)		$ 21.50
Proceeds from issuance of common stock, net of offering costs		$ 23,700
At the Market Offering
Subsidiary, Sale of Stock [Line Items]
Shares of common stock purchased (in shares)			62,342	599,284
Common stock maximum amount available for issuance	$ 75,000
Proceeds of stock sale			$ 1,100	$ 10,800

Collaboration and Other Agree28

Collaboration and Other Agreements - Janssen Biotech, Inc. (Details) - Janssen Biotech, Inc. - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	May 31, 2016	Dec. 31, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Janssen MGD011 Agreement
Collaboration and Other Agreements [Line Items]
Sale of common stock (in shares)		1,923,077
Proceeds of stock sale		$ 75,000,000
Non-refundable upfront payment		$ 50,000,000
Janssen MGD015 Agreement
Collaboration and Other Agreements [Line Items]
Non-refundable upfront payment	$ 75,000,000
Revenue recognized under agreement			$ 200,000	$ 0	$ 500,000	$ 75,000,000
Janssen MGD015 Agreement | Maximum
Collaboration and Other Agreements [Line Items]
Potential clinical milestone payments			100,000,000		100,000,000
Potential regulatory milestone payments under agreement			265,000,000		265,000,000
Potential sales milestone payments under agreement			$ 300,000,000		$ 300,000,000

Collaboration and Other Agree29

Collaboration and Other Agreements - Les Laboratoires Servier (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2014	Dec. 31, 2016
Collaboration And Other Agreements [Line Items]
Deferred revenue included in current liabilities		$ 3,202,000		$ 3,202,000			$ 4,261,000
Deferred revenue included in long-term liabilities		8,438,000		$ 8,438,000			10,045,000
Servier | Servier DART
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment	$ 20,000,000
Original period of development				29 months
Expected period of development				75 months
Change in accounting estimate current year impact				$ 800,000		$ 3,700,000
Option exercise fee						$ 15,000,000
Original Option Exercise Fee Recognition Period						82 months
Option exercise fee recognition period				124 months
Offset to research and development costs under the collaboration agreement		600,000	$ 1,000,000	$ 1,500,000	$ 2,100,000
Revenue recognized under agreement		600,000	$ 800,000	2,000,000	$ 2,500,000
Deferred revenue		9,100,000		9,100,000			11,100,000
Deferred revenue included in current liabilities		2,300,000		2,300,000			3,300,000
Deferred revenue included in long-term liabilities		6,800,000		6,800,000			$ 7,800,000
Servier | Servier DART | Maximum
Collaboration And Other Agreements [Line Items]
Potential license fee		40,000,000		40,000,000
Potential clinical milestone payments		63,000,000		63,000,000
Potential regulatory milestone payments under agreement		188,000,000		188,000,000
Potential sales milestone payments under agreement		$ 420,000,000		$ 420,000,000

Collaboration and Other Agree30

Collaboration and Other Agreements - NIAID Contract (Details) - NIAID	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)Molecule	Sep. 30, 2016USD ($)
Collaboration And Other Agreements [Line Items]
Commercialization of molecules | Molecule			2
Base period	$ 7,500,000		$ 7,500,000
Proceeds from additional development funding options under agreement	10,800,000
Revenue recognized under agreement	400,000	$ 1,200,000	1,500,000	$ 4,300,000
Maximum
Collaboration And Other Agreements [Line Items]
Additional development funding options under agreement	17,000,000		17,000,000
Total potential value	$ 24,500,000		$ 24,500,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	May 18, 2017	Dec. 31, 2016	Dec. 31, 2012	Feb. 28, 2003
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock				$ 34,294	$ 0
Options outstanding (in shares)		4,533,794		4,533,794			3,838,060
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 19.71		$ 19.71			$ 18.93
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 4,001	$ 3,003	$ 11,064	9,126
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)				19,351
Proceeds from issuance of common stock				$ 300
2003 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)								4,336,730	2,051,644
Options outstanding (in shares)		989,239		989,239
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 1.89		$ 1.89
Stock Incentive Plan 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)		6,769,888		6,769,888
Potential annual increase in shares reserved for future issuance (in shares)		1,960,168		1,960,168
Potential annual increase in shares reserved for future issuance as percentage of outstanding share				4.00%
Options outstanding (in shares)		3,544,555		3,544,555
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 24.69		$ 24.69
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 2,006	1,403	$ 5,512	4,243
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 1,995	$ 1,600	$ 5,552	$ 4,883

Stock-Based Compensation - Opti

Stock-Based Compensation - Option Pricing Assumptions (Details)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected term	6 years 3 months	6 years 3 months
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	66.70%	63.70%
Risk-free interest rate	1.90%	1.20%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	68.30%	67.70%
Risk-free interest rate	2.30%	2.10%

Stock-Based Compensation - St33

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding, Beginning Balance (in shares)	3,838,060
Shares, Granted (in shares)	1,219,725
Shares, Exercised (in shares)	(219,732)
Shares, Forfeited or expired (in shares)	(304,259)
Shares, Outstanding, Ending Balance (in shares)	4,533,794	3,838,060
Shares, Exercisable (in shares)	2,704,057
Shares, Vested and expected to vest (in shares)	4,352,976
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted- Average Exercise Price, Outstanding, Beginning Balance (in dollars per share)	$ 18.93
Weighted- Average Exercise Price, Granted (in dollars per share)	20.09
Weighted- Average Exercise Price, Exercised (in dollars per share)	2.02
Weighted- Average Exercise Price, Forfeited or expired (in dollars per share)	24.13
Weighted- Average Exercise Price, Outstanding, Ending Balance (in dollars per share)	19.71	$ 18.93
Weighted- Average Exercise Price, Exercisable (in dollars per share)	16.86
Weighted- Average Exercise Price, Vested and expected to vest (in dollars per share)	$ 19.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted- Average Remaining Contractual Term, Outstanding	7 years 2 months 19 days	7 years
Weighted- Average Remaining Contractual Term, Exercisable	6 years 2 months 12 days
Weighted- Average Remaining Contractual Term, Vested and expected to vest	7 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 18,050
Aggregate Intrinsic Value, Exercisable	17,254
Aggregate Intrinsic Value, Vested and expected to vest	$ 17,993
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 12.56
Intrinsic value of options exercised	$ 3,700
Cash received for options exercised	400
Fair value of shares vested	10,700
Unrecognized compensation expense related to non-vested stock-options, net of related forfeiture estimates	$ 23,700
Unrecognized compensation expense recognition period	2 years 6 months

Commitments and Contingencies34

Commitments and Contingencies (Details) $ in Thousands	Jul. 21, 2017USD ($)	Jul. 06, 2017USD ($)	Apr. 30, 2017	Jul. 31, 2015USD ($)	Sep. 30, 2017USD ($)Lease
Commitments and Contingencies Disclosure [Abstract]
Number of Lease | Lease					5
Term of operating leases		30 months	72 months
Lease incentives	$ 7,500			$ 5,100
Future sublease payments to be received		$ 2,400			$ 300
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,017					6,985
2,018					6,574
2,019					6,342
2,020					4,775
2,021					4,743
Thereafter					23,370
Total					$ 52,789

Net Loss Per Share - Narrative

Net Loss Per Share - Narrative (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Stock options excluded from computation of earnings per share (in shares)	4,533,794	3,856,652	4,533,794	3,856,652

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Income (Loss) Per Common Share Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss used for calculation of basic and diluted EPS	$ (47,043)	$ (33,846)	$ (125,353)	$ (23,745)
Denominator:
Weighted average shares outstanding, basic (in shares)	36,779,305	34,766,440	35,847,449	34,629,330
Effect of dilutive securities:
Stock options and restricted stock units (in shares)	0	0	0	0
Weighted average shares outstanding, diluted	36,779,305	34,766,440	35,847,449	34,629,330
Basic and diluted net loss per common share (in usd per share)	$ (1.28)	$ (0.97)	$ (3.50)	$ (0.69)

Subsequent Event (Details)

Subsequent Event (Details) - Incyte Corporation - Incyte MGA012 Agreement - Subsequent Event $ in Millions	1 Months Ended
	Oct. 31, 2017USD ($)
Subsequent Event [Line Items]
Non-refundable upfront payment	$ 150
Minimum
Subsequent Event [Line Items]
Potential royalty revenue percent	15.00%
Maximum
Subsequent Event [Line Items]
Potential clinical, regulatory and commercialization milestone payments	$ 750
Potential royalty revenue percent	24.00%