MacroGenics (MGNX) 10-Q 6 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Entity Registrant Name	MACROGENICS INC
Entity Central Index Key	1125345
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	No
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		30,047,629

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$263,134	$157,591
Accounts receivable	1,719	2,935
Prepaid expenses	3,617	4,211
Total current assets	268,470	164,737
Restricted cash	300	300
Property and equipment, net	7,236	6,785
Other assets	2,064	2,064
Total assets	278,070	173,886
Current liabilities:
Accounts payable	1,444	1,669
Accrued expenses	7,001	7,930
Lease exit liability	1,696	1,642
Deferred revenue	12,382	14,248
Other liabilities	1,605	1,605
Total current liabilities	24,128	27,094
Lease exit liability, net of current portion	5,914	6,364
Deferred rent liability	2,646	2,670
Deferred revenue, net of current portion	14,389	16,472
Total liabilities	47,077	52,600
Stockholders' equity:
Common stock, $0.01 par value - 125,000,000 shares authorized, 30,024,535 and 27,995,638 shares outstanding at March 31, 2015 and December 31, 2014, respectively	300	280
Treasury stock, at cost; 865 shares at March 31, 2015 and December 31, 2014	-19	-19
Additional paid-in capital	399,629	335,071
Accumulated deficit	-168,917	-214,046
Total stockholders' equity	230,993	121,286
Total liabilities and stockholders' equity	$278,070	$173,886

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
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)	30,024,535	27,995,638
Treasury stock, shares (in shares)	865	865

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues:
Revenue from collaborative research	$71,165	$14,401
Grant revenue	114	318
Total revenues	71,279	14,719
Costs and expenses:
Research and development	21,464	14,569
General and administrative	4,683	3,258
Total costs and expenses	26,147	17,827
Income (loss) from operations	45,132	-3,108
Other income (expense)	-3	0
Net comprehensive income (loss)	$45,129	($3,108)
Basic net income (loss) per common share (in dollars per share)	$1.53	($0.12)
Diluted net income (loss) per common share (in dollars per share)	$1.42	($0.12)
Weighted average shares outstanding, basic	29,415,768	26,262,356
Diluted weighted average common shares outstanding (in shares)	31,684,174	26,262,356

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities
Net income (loss) used for calculation of basic and diluted EPS	$45,129	($3,108)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation expense	546	398
Share-based compensation	1,631	612
Changes in operating assets and liabilities:
Accounts receivable	1,216	258
Prepaid expenses	594	-965
Other assets	0	-1,394
Accounts payable	-225	1,964
Accrued expenses	-929	-848
Lease exit liability	-396	-348
Deferred revenue	-3,949	9,423
Deferred rent	-24	-106
Net cash provided by operating activities	43,593	5,886
Cash flows from investing activities
Purchases of property and equipment	-997	-447
Net cash used in investing activities	-997	-447
Cash flows from financing activities
Proceeds from issuance of common stock, net of offering costs	62,692	76,733
Proceeds from stock option exercises	255	68
Net cash provided by financing activities	62,947	76,801
Net change in cash and cash equivalents	105,543	82,240
Cash and cash equivalents at beginning of period	157,591	116,481
Cash and cash equivalents at end of period	$263,134	$198,721

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies
	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 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2015.
	There have been no material changes to the significant accounting policies previously disclosed in the Company's 2014 Annual Report on Form 10-K.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2015
Fair Value of Financial Instruments [Abstract]
Fair Value of Financial Instruments	2. Fair Value of Financial Instruments
	The fair market values of the financial instruments included in the financial statements, which include cash equivalents and money market accounts, approximate their carrying values at March 31, 2015 due to their short-term maturities. The Company accounts for recurring and non-recurring fair value measurements in accordance with Financial Accounting Standards Board (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 and liabilities subject to fair value measurements were as follows (in thousands):
		Fair Value Measurements at March 31, 2015
					Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		Total			Level 1			Level 2			Level 3
	Assets:
	Cash and cash equivalents		$	237,088		$	237,088		$	—		$	—
	Money market funds			26,046			26,046			—			—
	Restricted cash			300			300			—			—
	Total Assets		$	263,434		$	263,434		$	—		$	—
		Fair Value Measurements at December 31, 2014
					Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		Total			Level 1			Level 2			Level 3
	Assets:
	Cash and cash equivalents		$	131,545		$	131,545		$	—		$	—
	Money market funds			26,046			26,046			—			—
	Restricted cash			300			300			—			—
	Total Assets		$	157,891		$	157,891		$	—		$	—

Lease_Exit_Liability

Lease Exit Liability	3 Months Ended
	Mar. 31, 2015
Lease Exit Liability [Abstract]
Lease Exit Liability	3. Lease Exit Liability
	On July 16, 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. Raven was considered a development-stage enterprise as defined in ASC 915, Development Stage Entities.
	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. The terms of the operating lease extend into 2018.
	Changes in the lease exit liability are as follows (in thousands):
	Accrual balance at December 31, 2014	$	8,006
	Principal payments		(396	)
	Accrual balance at March 31, 2015	$	7,610
	The purchase agreement provides for a specified total of certain contingent milestones that are based on the achievement of certain product sales derived from the acquired Raven technology. Also, a onetime payment of $5.0 million will be made to the Raven stockholders upon the initiation of patient dosing in the first Phase 2 clinical trial of any product derived from the Raven "Cancer Stem Cell Program." No payment shall be made if the Phase 2 trial start date has not occurred on or before July 15, 2018. Other consideration includes a percentage of revenue (excluding consideration for research and development and equity) received by MacroGenics for license of a product derived from the Raven "Cancer Stem Cell Program" and a onetime payment ranging from $8.0 million to $12.0 million dependent upon a specified level of sales of products derived from the Raven "Cancer Stem Cell Program."
	Any contingent consideration would be accounted for as additional purchase price and recorded as incremental in-process research and development expense when and if it is deemed probable that the contingencies will be attained. No additional amounts have been recorded during the three months ended March 31, 2015 and 2014.

Collaboration_and_License_Agre

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2015
Collaboration and License Agreements [Abstract]
Collaboration and License Agreements	4. Collaboration and License 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, a product candidate that incorporates the Company's proprietary Dual Affinity Re-Targeting (DART) technology to simultaneously target CD19 and CD3 for the potential treatment of B-cell malignancies. The Company contemporaneously entered into a stock purchase agreement and investor agreement, each with Johnson & Johnson Innovation – JJDC, Inc. (JJDC).  JJDC agreed to purchase 1,923,077 new shares of the Company's common stock at a price of $39.00 per share, representing proceeds of $75.0 million. The effectiveness of these agreements was subject to the early termination or expiration of any applicable waiting periods under Hart-Scott-Rodino Antitrust Improvements Act of 1976.  The waiting period expired in January 2015, at which time the Company received a $50.0 million upfront payment from Janssen and JJDC purchased $75.0 million of the Company's common stock.
	Under the collaboration and license agreement, the Company granted an exclusive license to Janssen to develop and commercialize MGD011. Following the Company's submission of the Investigational New Drug (IND) application, Janssen will be fully responsible for the development and commercialization of MGD011.   Assuming successful development and commercialization, the Company could receive up to an additional $205.0 million in clinical milestone payments, $220.0 million in regulatory milestone payments and $150.0 million in commercialization milestone payments. The Company determined that each potential future clinical, development, 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 in the U.S. and Canada. If commercialized, the Company would be eligible to receive double-digit royalties on any global net sales and has the option to co-promote the molecule with Janssen in the U.S.
	The Company evaluated the collaboration and license agreement with Janssen and determined that it is a revenue arrangement with multiple deliverables, or performance obligations.  The Company's substantive performance obligations under the collaboration and license agreement include the delivery of an exclusive license and research and development services during the pre-clinical research period (through the filing of the IND for MGD011).   The Company evaluated the collaboration and license agreement with Janssen and determined that the license and pre-clinical research and development activities represented one unit of accounting, and thus the total arrangement consideration was allocated using the relative selling price method to the deliverables.  After identifying the deliverables included within the arrangement, the Company determined its best estimate of selling price for each of the deliverables.  The best estimate of selling price for the exclusive license was determined using a discounted cash flow model that includes level 3 fair value measurements. The best estimate of selling price for the research and development services was determined using third party evidence of other similar research and development arrangements, which are level 2 fair value measurements.
	The Company evaluated the stock purchase agreement and the collaboration and license agreement as one arrangement and determined that the stock purchase price of $39.00 per share exceeded the fair value of the common stock by $12.3 million. This excess was recognized in the same manner as the upfront payment.  Of the total arrangement consideration of $125.0 million, the Company allocated $62.7 million to equity (representing the fair value of common stock purchased), $62.3 million to the license and pre-clinical research and development activities, and a de minimis amount to the ongoing research and development activities.  The Company submitted the IND and therefore met its performance obligation during the three months ended March 31, 2015.
	During the three months ended March 31, 2015, the Company recognized revenues of approximately $62.3 million under the agreement.
	Takeda Pharmaceutical Company Limited
	In May 2014, the Company entered into a license and option agreement with Takeda Pharmaceutical Company Limited (Takeda) for the development and commercialization of MGD010, a product candidate that incorporates the Company's proprietary DART technology to simultaneously engage CD32B and CD79B, which are two B-cell surface proteins. MGD010 is being developed for the treatment of autoimmune disorders. Upon execution of the agreement, Takeda made a non-refundable payment of $15.0 million to the Company. Takeda has an option to obtain an exclusive worldwide license for MGD010 following the completion of a pre-defined Phase 1a study. The Company will lead all product development activities until that time. If Takeda exercises its option, it will assume responsibility for future development and pay the Company a license fee of $15.0 million. Assuming successful development and commercialization of MGD010, the Company is eligible to receive up to an additional $93.0 million in clinical and regulatory milestone payments and $375.5 million in sales milestone payments. If commercialized, the Company would receive double-digit royalties on any global net sales and has the option to co-promote MGD010 with Takeda in the United States. Finally, the Company may elect to fund a portion of Phase 3 clinical development in exchange for a North American profit share.
	The Company evaluated the license and option agreement with Takeda and determined that it is a revenue arrangement with multiple deliverables, or performance obligations. The Company's substantive performance obligations under the license and option agreement include exclusivity, research and development services through the Phase 1a study and delivery of a future license for an initial research compound. The Company concluded that the MGD010 option is substantive and that the license fee payable upon exercise of the option is not a deliverable at the inception of the arrangement as there is considerable uncertainty that the option would be exercised. The Company has determined that each potential future development 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. The Company determined that these performance obligations represent a single unit of accounting, because the exclusivity clause does not have stand-alone value to Takeda without the Company's technical expertise and development through the pre-defined Phase 1a study.
	After identifying the deliverables included within the arrangement, the Company determined its best estimate of selling price. The Company allocated $10.0 million to the exclusivity clause to its technology and the research and development services and $5.0 million to the exclusive license for the initial research compound. The Company's determination of best estimate of selling price for the research and development services relied upon other similar transactions. The Company relied upon the income approach (e.g., future cash flows) to determine the value of the license of the to-be-delivered compound along with other similar license transactions with differing indications but similar stage of development. The portion of the up-front fee allocated to the MGD010 option is being recognized over an initial 24-month period, which represents the expected period of development through the completion of a pre-defined Phase 1a study. The portion of the up-front fee allocated to the license for the initial research compound was deferred until the research collaboration and license option agreement was executed and the license delivered.
	The Company recognized revenue of approximately $4.3 million under the MGD010 agreement during the three months ended March 31, 2015, including a $3.0 million milestone payment due upon initiation of a Phase 1a trial of MGD010.   At March 31, 2015, $5.8 million of revenue was deferred under this agreement, $5.0 million of which was current and $0.8 million of which was non-current.  At December 31, 2014, $7.1 million of revenue was deferred under this agreement, $5.0 million of which was current and $2.1 million of which was non-current.
	In September 2014, the Company and Takeda executed a research collaboration and license option agreement, which formalized the license for the initial research compound contemplated in the May 2014 arrangement. Under the terms of the agreement, Takeda may identify up to three additional compounds, which will be subject to separate research and development plans. The Company determined that it could recognize the entire license fee as (1) the executed contract constituted persuasive evidence of an arrangement, (2) the delivery of the license occurred and the Company had no current or future performance obligations, (3) the total consideration for the license was fixed and known at the time of its execution and there were not any extended payment terms or rights of return, and (4) the cash was received.  The Company is also entitled to receive reimbursement for research and development services provided to Takeda with respect to the initial research compound under a separate research plan.  During the three months ended March 31, 2015, the Company recognized $0.3 million in revenue related to the reimbursement of these research and development services.
	Les Laboratoires Servier
	In November 2011, the Company entered into a right-to-develop collaboration agreement with Les Laboratoires Servier and Institut de Recherches Servier (collectively, Servier) for the development and commercialization of MGA271 in all countries other than the United States, Canada, Mexico, Japan, South Korea and India.
	Upon execution of the agreement, Servier made a non-refundable payment of $20.0 million to the Company. The Company is eligible to receive up to $30.0 million in license fees, $47.0 million in clinical milestone payments, $140.0 million in regulatory milestone payments and $208.0 million in sales milestone payments if Servier exercises the option, obtains regulatory approval for and successfully commercializes MGA271. The Company concluded that the license fees are not deliverables at the inception of the arrangement. The Company has determined that each potential future clinical, development 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. In the event Servier exercises its option to continue development of MGA271, Servier must pay a license fee. Under this agreement, Servier would be obligated to pay the Company from low double digit to mid-teen royalties on 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 the option is substantive and that the license fee for this option is not a deliverable at the inception of the arrangement as there is considerable uncertainty that the option would be exercised and the additional fee to be paid upon exercise of the option represents its estimated selling price (i.e., no substantial discount was given). 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 these performance obligations 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 payment was deferred and was being recognized ratably over the initial 27-month period, which represented the expected period of development and the Company's participation on the research and development committee. During 2014, the Company determined that the development period will last longer than originally estimated, and prospectively adjusted its period of recognition of the upfront payment to a 42-month period.
	During the three months ended March 31, 2015 and 2014, the Company recognized revenue of $0.1 million and $0.2 million, respectively, under this agreement. At March 31, 2015 and December 31, 2014, $36,000 and $0.1 million of revenue remained deferred under this agreement, respectively, all of which was current.
	In September 2012, the Company entered into a second right-to-develop collaboration agreement with Servier and granted it options to obtain three separate exclusive licenses to develop and commercialize DART-based molecules, consisting of those designated by the Company as MGD006 and MGD007, as well as a third DART molecule, in all countries other than the United States, Canada, Mexico, Japan, South Korea and India.
	Upon execution of the agreement, Servier made a non-refundable payment of $20.0 million to the Company. In addition, the Company will be eligible to receive up to $65.0 million in license fees, $98.0 million in clinical milestone payments, including $5.0 million upon IND acceptance for each of MGD006, MGD007 and a third DART molecule, $300.0 million in regulatory milestone payments and $630.0 million in sales milestone payments if Servier exercises all of the 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, development 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 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 during the first year of the agreement and participation on an executive committee and a research and development committee. The Company determined that the performance obligations with respect to the pre-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 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 DARTs 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.
	During the three months ended March 31, 2014, Servier exercised its exclusive option to develop and commercialize MGD006. As a result of the exercise, the Company received a $15.0 million payment from Servier for its license to develop and commercialize MGD006 in its territories. Upon exercise of the option, the Company evaluated its performance obligations with respect to the license for MGD006. 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 is being recognized ratably over a period of 82 months, which represents the expected development period for MGD006. In accordance with the agreement, the Company and Servier will share costs incurred to develop MGD006. 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 March 31, 2015, the Company recorded approximately $0.3 million as an offset to research and development costs under this collaboration arrangement, and has recorded a corresponding collaboration receivable, which is included in accounts receivable on the consolidated balance sheet.  No such offset to research and development costs was recorded during the three months ended March 31, 2014.
	The Company recognized revenue of $0.8 million and $7.4 million during the three months ended March 31, 2015 and 2014, respectively, under this agreement.  Revenue during the three months ended March 31, 2014 includes the $5.0 million payment from Servier upon the achievement of a clinical milestone related to the IND application for MGD006 clearing the 30-day review period by the U.S. Food and Drug Administration (FDA).  No milestones were recognized under this agreement during the three months ended March 31, 2015.
	At March 31, 2015, $16.9 million of revenue was deferred under this agreement, $3.3 million of which was current and $13.6 million of which was non-current. At December 31, 2014, $17.7 million of revenue was deferred under this agreement, $3.3 million of which was current and $14.4 million of which was non-current.
	Boehringer Ingelheim International GmbH
	In October 2010 the Company entered into a collaboration and license agreement with Boehringer Ingelheim International GmbH (Boehringer) to discover, develop and commercialize up to ten DART-based molecules which span multiple therapeutic areas. Under the terms of the agreement, the Company granted Boehringer an exclusive, worldwide, royalty-bearing license under its intellectual property to research, develop, and market DARTs generated under the agreement throughout the world.
	Upon execution of the agreement, the Company received an upfront payment of $15.0 million. The Company subsequently received three annual maintenance payments. These maintenance payments are being recognized over the estimated period of development. The Company has the potential to earn milestone payments of approximately $41.0 million related to pre-clinical and clinical development, $89.0 million related to regulatory milestones and $83.0 million related to sales milestones for each of the DART programs under this agreement in the case of full commercial success of multiple DART products. The Company has determined that each potential future clinical, development 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. Boehringer also provides funding for the Company's internal and external research costs and is required to pay the Company mid-single digit royalties on product sales.
	The Company determined that the deliverables under the Boehringer agreement include the license, the research and development services to be performed by the Company, and the co-promotion/manufacturing services. The Company concluded that the co-promotional activities were optional and were subject to further negotiation upon reaching regulatory approval. As such, the co-promotional period is not included in the expected obligation period to perform services.
	The Company concluded that the undelivered element of research and development services had fair value. The Company concluded that the license does not have value on a standalone basis (e.g., absent the provision of the research and development services) and therefore does not represent a separate unit of accounting. The Company concluded that because the drug candidate has not yet been developed, the license is of no value to Boehringer without the ensuing research and development activities using the DART technology, which is proprietary to the Company. Likewise, Boehringer could not sell the license to another party (without the Company agreeing to provide the research and development activities for the other party). Therefore, the upfront license fee and research and development services were treated as a combined unit of accounting and recognized over the expected obligation period associated with the research and development services through September 2015, which represents the estimated period of development.
	The Company and Boehringer have also agreed to establish a joint research committee to facilitate the governance and oversight of the parties' activities under the agreements. Management considered whether participation on the joint committee may be a deliverable and determined that it was not a deliverable. However, had management considered participation on the joint committee as a deliverable, it would not have had a material impact on the accounting for the arrangement as the period of participation in this committee matched the obligation period for the research and development services.
	The Company recognized revenues of approximately $2.6 million and $3.1 million during the three months ended March 31, 2015 and 2014, respectively.  At March 31, 2015, $4.0 million of revenue was deferred under this agreement, all of which was current. At December 31, 2014, $5.8 million of revenue was deferred under this agreement, all of which was current.
	There have been no material modifications to this agreement since the adoption of ASU 2009-13, Revenue Recognition – Multiple-Deliverable Revenue Arrangements, on January 1, 2011.
	Green Cross Corporation
	In June 2010, the Company entered into a collaboration agreement with Green Cross Corp. (Green Cross) for the development of the Company's anti-HER2 antibody margetuximab. This arrangement grants Green Cross an exclusive license to conduct specified Phase 1 and Phase 2 clinical trials and commercialize margetuximab in South Korea. In March 2014, the Company and Green Cross entered into an amendment to the original agreement, causing the terms of the original agreement to be materially modified.
	Upon execution of the amendment, the Company became eligible to receive reimbursement for costs incurred for Phase 2 and Phase 3 clinical trials up to $5.5 million as well as clinical development and commercial milestone payments of up to $2.5 million. The Company determined that each potential clinical development and commercial milestone is substantive. The Company is also entitled to receive royalties on net sales of margetuximab in South Korea. The Company and Green Cross have formed a joint steering committee to coordinate and oversee activities on which the companies collaborate under the agreement.
	The Company evaluated the collaboration agreement with Green Cross and determined that it is a revenue arrangement with multiple deliverables or performance obligations. As a result of the material modification to the arrangement in March 2014, the Company reassessed the entire arrangement in accordance with the guidance provided by ASC 605-25, Multiple Element Arrangements (Revenue Recognition) as the original agreement was accounted for prior to adopting ASU 2009-13. The Company's substantive performance obligations under this agreement include an exclusive license to its technologies, research and development services, and participation in a joint steering committee. The Company concluded that the license and the reimbursement for research and development services do not have value on a standalone basis and therefore do not represent a separate unit of accounting.
	The initial $1.0 million upfront payment received by the Company upon execution of the original agreement is non-refundable; as such, there is no right of return for the license. Therefore, the upfront license fee and participation on the joint steering committee were treated as a combined unit of accounting and will be recognized over the term of the agreement through June 2020. Further, due to the fact the research and development services are not deemed to have stand-alone value, revenue for those services should be recognized over the entire term of the agreement (through June 2020). As a result of reassessing the arrangement in accordance with ASC 605-25, the Company was required to record an adjustment on the date of the material modification to reflect the revenue that would have resulted had the entity applied the requirements of ASC 605-25 from the inception of the agreement. As a result, the Company recorded an additional $1.3 million of revenue during the three months ended March 31, 2014.
	The Company recognized revenues of approximately $0.1 million and $1.4 million under this agreement during the three months ended March 31, 2015 and 2014, respectively.  No milestones were achieved under this agreement during the three months ended March 31, 2015 and 2014.
	At March 31, 2015 and December 31, 2014, there was $0.6 million and $0.5 million in unbilled receivables under this agreement, which is included in other assets on the consolidated balance sheet.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Stock-Based Compensation [Abstract]
Stock-Based Compensation	5. Stock-Based Compensation
	The Company's 2000 Stock Option and Incentive Plan (2000 Plan) allowed for the grant of awards in respect of an aggregate of 150,297 shares of the Company's common stock in the form of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock and restricted stock units and other performance awards. The 2000 Plan has expired, and no further awards may be issued under the plan. Any shares of common stock subject to awards under the 2000 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.
	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 allowed for the grant of awards in respect of an aggregate of 4,336,731 shares of the Company's common stock. 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 October 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 Plan, up to a specified number of shares.
	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 aggregate number of shares of common stock initially available for issuance pursuant to awards under the 2013 Plan was 1,960,168 shares. 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. All of the shares available for issuance under the 2013 Plan are eligible for issuance pursuant to the exercise of incentive stock options. 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.
	The following stock-based compensation amounts were recognized for the periods indicated (in thousands):
		Three Months Ended March 31,
		2015				2014
	Research and development		$	810			$	317
	General and administrative			821				295
	Total stock-based compensation expense		$	1,631			$	612
	Employee Stock Options
	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:
		Three Months Ended March 31,
		2015		2014
	Expected dividend yield	0%		0%
	Expected volatility	74%		67%
	Risk-free interest rate	1.6% - 2.0%		2.1% - 2.3%
	Expected term	6.25 years		6.25 years
	The following table summarizes stock option activity under the Plan during the three months ended March 31, 2015:
			Shares				Weighted-		Weighted-Average		Aggregate
							Average		Remaining		Intrinsic
							Exercise Price		Contractual Term		Value
									(Years)		(in thousands)
	Outstanding, December 31, 2014			3,572,116			$	11.4		7.3
	Granted			39,975				32.91
	Exercised			(105,820	)			2.57
	Forfeited or expired			(16,618	)			17.59
	Outstanding, March 31, 2015			3,489,653				11.88		7.2		$	68,188
	March 31, 2015:
	Exercisable			1,697,219				3.8		5.3			46,834
	Vested and expected to vest			3,269,812				11.5		7.1			65,120
	The weighted-average grant-date fair value of options granted for the three months ended March 31, 2015 was $19.05. The total intrinsic value of options exercised during the three months ended March 31, 2015 was approximately $3.3 million, and the total cash received for options exercised was approximately $0.3 million. The total fair value of shares vested in the three months ended March 31, 2015 was approximately $0.8 million. As of March 31, 2015, the total unrecognized compensation expense related to non-vested stock options, net of related forfeiture estimates, was approximately $18.5 million, which the Company expects to recognize over a weighted-average period of approximately four years.

Net_Income_Loss_Per_Share

Net Income (Loss) Per Share	3 Months Ended
	Mar. 31, 2015
Net Income (Loss) Per Share [Abstract]
Net Income (Loss) Per Share	6. Net Income (Loss) Per Share
	Basic income (loss) per common share is determined by dividing income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted income (loss) per share is computed by dividing the income (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. 2,719,339 stock options (common stock equivalents) were excluded from the calculation of diluted loss per share allocable to common stockholders for the three months ended March 31, 2014 because their inclusion would have been anti-dilutive.
	Basic and diluted income (loss) per common share is computed as follows (in thousands except share and per share data):
		Three Months Ended March 31,
		2015		2014
	Numerator:
	Net income (loss) used for calculation of basic and diluted EPS	$	45,129	$	(3,108	)
	Denominator:
	Weighted average shares outstanding, basic		29,415,768		26,262,356
	Effect of dilutive securities:
	Stock options and restricted stock units		2,268,406		-
	Weighted average shares outstanding, diluted		31,684,174		26,262,356
	Net income (loss) per share, basic	$	1.53	$	(0.12	)
	Net income (loss) per share, diluted	$	1.42	$	(0.12	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Summary of Significant 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 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 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2015.
	There have been no material changes to the significant accounting policies previously disclosed in the Company's 2014 Annual Report on Form 10-K.

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value of Financial Instruments [Abstract]
Summary of Fair Value Measurement Financial Asset and Liabilities	Financial assets and liabilities subject to fair value measurements were as follows (in thousands):
		Fair Value Measurements at March 31, 2015
					Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		Total			Level 1			Level 2			Level 3
	Assets:
	Cash and cash equivalents		$	237,088		$	237,088		$	—		$	—
	Money market funds			26,046			26,046			—			—
	Restricted cash			300			300			—			—
	Total Assets		$	263,434		$	263,434		$	—		$	—
		Fair Value Measurements at December 31, 2014
					Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		Total			Level 1			Level 2			Level 3
	Assets:
	Cash and cash equivalents		$	131,545		$	131,545		$	—		$	—
	Money market funds			26,046			26,046			—			—
	Restricted cash			300			300			—			—
	Total Assets		$	157,891		$	157,891		$	—		$	—

Lease_Exit_Liability_Tables

Lease Exit Liability (Tables)	3 Months Ended
	Mar. 31, 2015
Lease Exit Liability [Abstract]
Changes in Lease Exit Liability	Changes in the lease exit liability are as follows (in thousands):
	Accrual balance at December 31, 2014	$	8,006
	Principal payments		(396	)
	Accrual balance at March 31, 2015	$	7,610

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Stock-Based Compensation [Abstract]
Schedule of Stock-Based Compensation Expense	The following stock-based compensation amounts were recognized for the periods indicated (in thousands):
		Three Months Ended March 31,
		2015				2014
	Research and development		$	810			$	317
	General and administrative			821				295
	Total stock-based compensation expense		$	1,631			$	612
Schedule of Fair Value Option Award Estimated on the Date of Grant 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:
		Three Months Ended March 31,
		2015		2014
	Expected dividend yield	0%		0%
	Expected volatility	74%		67%
	Risk-free interest rate	1.6% - 2.0%		2.1% - 2.3%
	Expected term	6.25 years		6.25 years
Schedule of Stock Option Activity	The following table summarizes stock option activity under the Plan during the three months ended March 31, 2015:
			Shares				Weighted-		Weighted-Average		Aggregate
							Average		Remaining		Intrinsic
							Exercise Price		Contractual Term		Value
									(Years)		(in thousands)
	Outstanding, December 31, 2014			3,572,116			$	11.4		7.3
	Granted			39,975				32.91
	Exercised			(105,820	)			2.57
	Forfeited or expired			(16,618	)			17.59
	Outstanding, March 31, 2015			3,489,653				11.88		7.2		$	68,188
	March 31, 2015:
	Exercisable			1,697,219				3.8		5.3			46,834
	Vested and expected to vest			3,269,812				11.5		7.1			65,120

Net_Income_Loss_Per_Share_Tabl

Net Income (Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Net Income (Loss) Per Share [Abstract]
Computation of Basic and Diluted Income (Loss) Per Common Share	Basic and diluted income (loss) per common share is computed as follows (in thousands except share and per share data):
		Three Months Ended March 31,
		2015		2014
	Numerator:
	Net income (loss) used for calculation of basic and diluted EPS	$	45,129	$	(3,108	)
	Denominator:
	Weighted average shares outstanding, basic		29,415,768		26,262,356
	Effect of dilutive securities:
	Stock options and restricted stock units		2,268,406		-
	Weighted average shares outstanding, diluted		31,684,174		26,262,356
	Net income (loss) per share, basic	$	1.53	$	(0.12	)
	Net income (loss) per share, diluted	$	1.42	$	(0.12	)

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets:
Cash and cash equivalents	$237,088	$131,545
Money market funds	26,046	26,046
Restricted cash	300	300
Total Assets	263,434	157,891
Quoted Prices in Active Markets for Identical Assets Level 1 [Member]
Assets:
Cash and cash equivalents	237,088	131,545
Money market funds	26,046	26,046
Restricted cash	300	300
Total Assets	263,434	157,891
Quoted Prices in Active Markets for Identical Assets Level 2 [Member]
Assets:
Cash and cash equivalents	0	0
Money market funds	0	0
Restricted cash	0	0
Total Assets	0	0
Quoted Prices in Active Markets for Identical Assets Level 3 [Member]
Assets:
Cash and cash equivalents	0	0
Money market funds	0	0
Restricted cash	0	0
Total Assets	$0	$0

Lease_Exit_Liability_Details

Lease Exit Liability (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jul. 16, 2008
Restructuring Cost and Reserve [Line Items]
Lease expiration year	2018
Restructuring Costs [Abstract]
Onetime purchase payment under purchase agreement			$5,000,000
Incremental in-process research and development expense	0	0
Minimum [Member]
Restructuring Costs [Abstract]
Onetime payment paid under license of product			8,000,000
Maximum [Member]
Restructuring Costs [Abstract]
Onetime payment paid under license of product			12,000,000
Contract Termination [Member]
Restructuring Costs [Abstract]
Accrual beginning balance	8,006,000
Principal payments	-396,000
Accrual ending balance	$7,610,000

Collaboration_and_License_Agre1

Collaboration and License Agreements, Janssen Biotech, Inc. (Details) (USD $)	1 Months Ended			3 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	31-May-14	Jan. 31, 2015	Dec. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment	$15
Janssen Biotech, Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sale of common stock (in shares)			1,923,077
Sale of common stock (in dollars per share)			$39		$39
Proceeds of stock sale					75
Additional Potential Clinical Milestone Payments Under Agreement				205
Additional Potential Regulatory Milestone Payments Under Agreement				220
Additional Potential Sales Milestone Payments Under Agreement				150
Premium received on stock purchase				12.3
Recognized revenue under agreement				62.3
Non-refundable upfront payment		$50

Collaboration_and_License_Agre2

Collaboration and License Agreements, Takeda Pharmaceutical Company Limited (Details) (USD $)	1 Months Ended	3 Months Ended
	31-May-14	Mar. 31, 2015	Dec. 31, 2014
License And Collaboration Agreements [Line Items]
Non-refundable upfront payment	$15,000,000
Deferred revenue current		12,382,000	14,248,000
Deferred revenue non-current		14,389,000	16,472,000
Takeda Pharmaceutical Company Limited [Member]
License And Collaboration Agreements [Line Items]
Collaboration agreement date		May-14
License option fee		15,000,000
Upfront fee allocated to agreement		10,000,000
Expected period of development		24 months
Recognized revenue under agreement		4,300,000
Deferred revenue		5,800,000	7,100,000
Deferred revenue current		5,000,000	5,000,000
Deferred revenue non-current		800,000	2,100,000
Revenue Recognition, Milestone Method, Revenue Recognized		3,000,000
Additional Potential Sales Milestone Payments Under Agreement		375,500,000
Additional Potential Clinical And Regulatory Milestone Payments Under Agreement		93,000,000
Takeda Pharmaceutical Company Limited [Member] | Research Collaboration And License Option Agreement [Member]
License And Collaboration Agreements [Line Items]
Upfront fee allocated to agreement		5,000,000
Research and development services revenue		$300,000

Collaboration_and_License_Agre3

Collaboration and License Agreements, Les Laboratoires Servier (Details) (USD $)	1 Months Ended		3 Months Ended		1 Months Ended
	31-May-14	Nov. 30, 2011	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2012	Dec. 31, 2014
License And Collaboration Agreements [Line Items]
Non-refundable upfront payment	$15,000,000
Deferred revenue included in current liabilities			12,382,000			14,248,000
Deferred revenue included in long-term liabilities			14,389,000			16,472,000
Servier [Member] | Servier MGA271 [Member]
License And Collaboration Agreements [Line Items]
Collaboration agreement date			Nov-11
Non-refundable upfront payment		20,000,000
Additional license grant fees			30,000,000
Additional Potential Clinical Milestone Payments Under Agreement			47,000,000
Additional Potential Regulatory Milestone Payments Under Agreement			140,000,000
Additional Potential Sales Milestone Payments Under Agreement			208,000,000
Original period of development			27 months
Expected period of development			42 months
Recognized revenue under agreement			100,000	200,000
Milestone payment				0
Deferred revenue			36,000			100,000
Servier [Member] | Servier DART [Member]
License And Collaboration Agreements [Line Items]
Collaboration agreement date			Sep-12
Non-refundable upfront payment					20,000,000
Additional license grant fees			65,000,000
Additional Potential Clinical Milestone Payments Under Agreement			98,000,000
Additional Potential Regulatory Milestone Payments Under Agreement			300,000,000
Additional Potential Sales Milestone Payments Under Agreement			630,000,000
Original period of development			29 months
Expected period of development			75 months
Recognized revenue under agreement			800,000	7,400,000
Milestone payment			0
Deferred revenue			16,900,000			17,700,000
License option fees received				15,000,000
Clinical milestone payments received under agreement				5,000,000
Offset to research and development costs under collaboration arrangement			300,000
Expected development period			82 months
Clinical milestone payments under agreement				5,000,000
Review period			30 days
Deferred revenue included in current liabilities			3,300,000			3,300,000
Deferred revenue included in long-term liabilities			$13,600,000			$14,400,000

Collaboration_and_License_Agre4

Collaboration and License Agreements, Boehringer Ingelheim International GmbH (Details) (USD $)	1 Months Ended		3 Months Ended
	31-May-14	Oct. 31, 2010	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
		Molecule	Payment
License And Collaboration Agreements [Line Items]
Non-refundable upfront payment	$15,000,000
Deferred revenue included in current liabilities			12,382,000		14,248,000
Deferred revenue included in long-term liabilities			14,389,000		16,472,000
Boehringer [Member]
License And Collaboration Agreements [Line Items]
Collaboration agreement date			Oct-10
Commercialization of molecules		10
Non-refundable upfront payment		15,000,000
Number of annual maintenance payments received			3
Additional Potential Clinical Milestone Payments Under Agreement			41,000,000
Additional Potential Regulatory Milestone Payments Under Agreement			89,000,000
Additional Potential Sales Milestone Payments Under Agreement			83,000,000
Research obligation completion date			Sep-15
Clinical milestone payments under agreement
Recognized revenue under agreement			2,600,000	3,100,000
Deferred revenue			4,000,000		5,800,000
Deferred revenue included in current liabilities			4,000,000		5,800,000
Deferred revenue included in long-term liabilities			0		0
Milestone payment

Collaboration_and_License_Agre5

Collaboration and License Agreements, Green Cross Corporation (Details) (USD $)	1 Months Ended		3 Months Ended
	31-May-14	Jun. 30, 2010	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
License And Collaboration Agreements [Line Items]
Non-refundable upfront payment	$15,000,000
Deferred revenue included in current liabilities			12,382,000		14,248,000
Deferred revenue included in long-term liabilities			14,389,000		16,472,000
Green Cross [Member]
License And Collaboration Agreements [Line Items]
Collaboration agreement date			Jun-10
Term of the agreement			Jun-20
Non-refundable upfront payment		1,000,000
Adjustment to revenue			1,300,000
Recognized revenue under agreement			100,000	1,400,000
Milestones achieved			0	0
Deferred revenue					0
Unbilled receivable balance			0.6		0.5
Deferred revenue included in current liabilities					0
Deferred revenue included in long-term liabilities					0
Green Cross [Member] | Maximum [Member]
License And Collaboration Agreements [Line Items]
Aggregate potential future cost reimbursement			5,500,000
Additional Potential Clinical Milestone Payments Under Agreement			$2,500,000

StockBased_Compensation_StockB

Stock-Based Compensation, Stock-Based Compensation Expense (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Oct. 31, 2013	Sep. 30, 2014	Feb. 28, 2003
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$1,631	$612
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	810	317
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$821	$295
2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)			1,960,168
Potential annual increase in shares reserved for future issuance			1,960,168
Potential annual increase in shares reserved for future issuance as percentage of outstanding share			4.00%
Stock Option Plan 2000 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)				150,297
Equity Incentive Plan 2003 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)					4,336,731

StockBased_Compensation_Option

Stock-Based Compensation, Option Pricing Assumptions (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield (in hundredths)	0.00%	0.00%
Expected volatility (in hundredths)	74.00%	67.00%
Expected term	6 years 3 months	6 years 3 months
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (in hundredths)
Risk-free interest rate (in hundredths)	1.60%	2.10%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (in hundredths)
Risk-free interest rate (in hundredths)	2.00%	2.30%

StockBased_Compensation_Stock_

Stock-Based Compensation, Stock Option Activity (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Stock-Based Compensation [Abstract]
Shares, Outstanding, Beginning Balance (in shares)	3,572,116
Shares, Granted (in shares)	39,975
Shares, Exercised (in shares)	-105,820
Shares, Forfeited or expired (in shares)	-16,618
Shares, Outstanding, Ending Balance (in shares)	3,489,653		3,572,116
Shares, Exercisable (in shares)	1,697,219
Shares, Vested and expected to vest (in shares)	3,269,812
Weighted- Average Exercise Price, Outstanding, Beginning Balance (in dollars per share)	$11.40
Weighted- Average Exercise Price, Granted (in dollars per share)	$32.91
Weighted- Average Exercise Price, Exercised (in dollars per share)	$2.57
Weighted- Average Exercise Price, Forfeited or expired (in dollars per share)	$17.59
Weighted- Average Exercise Price, Outstanding, Ending Balance (in dollars per share)	$11.88		$11.40
Weighted- Average Exercise Price, Exercisable (in dollars per share)	$3.80
Weighted- Average Exercise Price, Vested and expected to vest (in dollars per share)	$11.50
Weighted- Average Remaining Contractual Term, Outstanding	7 years 2 months 12 days		7 years 3 months 18 days
Weighted- Average Remaining Contractual Term, Exercisable	5 years 3 months 18 days
Weighted- Average Remaining Contractual Term, Vested and expected to vest	7 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$68,188,000
Aggregate Intrinsic Value, Exercisable	46,834,000
Aggregate Intrinsic Value, Vested and expected to vest	65,120,000
Weighted-average grant-date fair value of options granted (in dollars per share)	$19.05
Intrinsic value of options exercised	3,300,000
Cash received for options exercised	255,000	68,000
Fair value of shares vested	800,000
Unrecognized compensation expense related to non-vested stock-options, net of related forfeiture estimates	$18,500,000
Unrecognized compensation expense recognition period	4 years

Net_Income_Loss_Per_Share_Deta

Net Income (Loss) Per Share (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net Income (Loss) Per Share [Abstract]
Net income (loss) used for calculation of basic and diluted EPS	$45,129,000	($3,108,000)
Weighted average shares outstanding, basic	29,415,768	26,262,356
Net income (loss) per share, basic	$1.53	($0.12)
Basic weighted average common shares outstanding (in shares)	29,415,768	26,262,356
Stock options and restricted stock units	2,268,406	0
Weighted average shares outstanding, diluted	31,684,174	26,262,356
Diluted income (loss) per common share (in dollars per share)	$1.42	($0.12)
Stock Options (in shares)		2,719,339