Coherus BioSciences (CHRS) 10-K 23 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 28, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	CHRS
Entity Registrant Name	Coherus BioSciences, Inc.
Entity Central Index Key	1512762
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		33,324,459
Entity Public Float			$0

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$150,392,000	$39,554,000
Restricted cash	60,000	50,000
Receivables from collaboration and license agreement	2,417,000	278,000
Notes receivable	1,815,000
Notes receivable from related parties		107,000
Prepaid assets	20,485,000	5,688,000
Other assets	2,276,000
Other assets - related party	1,691,000
Total current assets	179,136,000	45,677,000
Property and equipment, net	4,472,000	1,743,000
Intangible assets	2,620,000
Goodwill	943,000
Other assets, non-current	50,000	27,000
Total assets	187,221,000	47,447,000
Current liabilities:
Accounts payable	8,778,000	3,302,000
Accounts payable - related parties	2,020,000	383,000
Accrued liabilities	11,231,000	7,258,000
Advance payments under license agreement	1,192,000
Deferred revenue	22,800,000	14,283,000
Convertible notes		1,111,000
Convertible notes - related parties		3,092,000
Contingent consideration	5,710,000
Convertible preferred stock warrant liability		24,251,000
Other liabilities	52,000	21,000
Total current liabilities	51,783,000	53,701,000
Deferred revenue, non-current	39,899,000	28,567,000
Contingent liability to collaborator	27,650,000	7,500,000
Contingent consideration, non-current	785,000
Other liabilities, non-current	347,000	61,000
Total liabilities	120,464,000	89,829,000
Commitments and contingencies (Note 8)
Convertible preferred stock		54,695,000
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value; Shares authorized: 5,000,000 at December 31, 2014; Shares issued and outstanding: no shares at December 31, 2014 and 2013.
Common stock, $0.0001 par value; Shares authorized: 300,000,000 at December 31, 2014; Shares issued and outstanding: 33,257,978 and 4,837,715 at December 31, 2014 and 2013, respectively	3,000	1,000
Additional paid-in capital	254,048,000	2,514,000
Accumulated other comprehensive loss	-525,000
Accumulated deficit	-186,725,000	-99,592,000
Total Coherus stockholders' equity (deficit)	66,801,000	-97,077,000
Non-controlling interest	-44,000
Total stockholders' equity (deficit)	66,757,000	-97,077,000
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	187,221,000	47,447,000
Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		1,191,000
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		$53,504,000

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Convertible preferred stock, shares authorized		28,090,997
Convertible preferred stock, shares issued		9,153,906
Convertible preferred stock, shares outstanding	0	9,153,906
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	300,000,000
Common stock, shares issued	33,257,978	4,837,715
Common stock, shares outstanding	33,257,978	4,837,715
Series A Convertible Preferred Stock
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	0	1,800,000
Convertible preferred stock, shares issued	0	972,330
Convertible preferred stock, shares outstanding	0	972,330
Series B Convertible Preferred Stock
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	0	26,290,997
Convertible preferred stock, shares issued	0	8,181,576
Convertible preferred stock, shares outstanding	0	8,181,576

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Collaboration and license revenue	$30,374,000	$2,751,000	$1,899,000
Other revenue	732,000
Total revenue	31,106,000	2,751,000	1,899,000
Operating expenses:
Research and development (includes related party of $21,723, $9,471 and $16,777 for the years ended December 31, 2014, 2013 and 2012, respectively)	78,224,000	31,279,000	34,886,000
General and administrative (includes related party of $597, $18 and $61 for the years ended December 31, 2014, 2013 and 2012, respectively)	17,564,000	7,465,000	5,531,000
Total operating expenses	95,788,000	38,744,000	40,417,000
Loss from operations	-64,682,000	-35,993,000	-38,518,000
Interest expense (includes related party of $2,687, $4,026 and $1,059 for the years ended December 31, 2014, 2013 and 2012, respectively)	-3,900,000	-5,293,000	-1,514,000
Other income (expense), net	-18,595,000	-12,349,000	7,014,000
Net loss	-87,177,000	-53,635,000	-33,018,000
Net loss attributable to non-controlling interest	44,000
Net loss attributable to Coherus	-87,133,000	-53,635,000	-33,018,000
Net loss per share attributable to Coherus, basic and diluted	($10.64)	($16.10)	($15.85)
Weighted-average number of shares used in computing net loss per share attributable to Coherus, basic and diluted	8,186,529	3,332,020	2,082,622
Baxter License Agreement
Revenue:
Collaboration and license revenue	28,481,000	726,000
Daiichi Sankyo - Related Party
Revenue:
Collaboration and license revenue	$1,893,000	$2,025,000	$1,899,000

Consolidated_Statements_of_Ope1

Consolidated Statements of Operations (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Research and development from transactions with related party	$21,723	$9,471	$16,777
General and administrative expenses from transactions with related party	597	18	61
Interest expense from transactions with related party	$2,687	$4,026	$1,059

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	($87,177)	($53,635)	($33,018)
Other comprehensive loss:
Foreign currency translation adjustments, net of tax	-525
Comprehensive loss	-87,702	-53,635	-33,018
Comprehensive loss attributable to non-controlling interest	44
Comprehensive loss attributable to Coherus	($87,658)	($53,635)	($33,018)

Consolidated_Statements_of_Con

Consolidated Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (USD $)	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss)	Accumulated Deficit	Total Coherus Stockholder Equity (Deficit)	Noncontrolling Interest	IPO	IPO	IPO	IPO	IPO	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Series C Convertible Preferred Stock
In Thousands, except Share data	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	Common Stock	Common Stock	Additional Paid-In Capital	Total Coherus Stockholder Equity (Deficit)	USD ($)	IPO	USD ($)	IPO	USD ($)	IPO
									USD ($)	Warrant	USD ($)	USD ($)		USD ($)		USD ($)		USD ($)
Beginning Balances at Dec. 31, 2011													$1,191
Beginning Balances, Shares at Dec. 31, 2011													972,330
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares															1,524,134
Issuance of common stock options in exchange for services															3,500
Ending Balances at Jan. 31, 2012
Beginning Balances at Dec. 31, 2011													1,191
Beginning Balances at Dec. 31, 2011	-2,307	1	5,658		-7,966	-2,307
Beginning Balances, Shares at Dec. 31, 2011													972,330
Beginning Balances, Shares at Dec. 31, 2011		5,098,977
Beneficial conversion feature related to convertible notes issued in 2011/2013	-10,631		-5,658		-4,973	-10,631
Issuance of convertible preferred stock net of issuance costs															26,938
Issuance of convertible preferred stock net of issuance costs, Shares															4,372,824
Issuance of convertible preferred stock value upon conversion of convertible promissory notes															10,631
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares															1,524,134
Issuance of convertible preferred stock in exchange for services															15,535
Issuance of convertible preferred stock in exchange for services, Shares															2,227,271
Issuance of convertible preferred stock upon exercise of warrants, including the reclassification of the associated convertible preferred stock warrant liability															400
Issuance of convertible preferred stock upon exercise of warrants, including the reclassification of the associated convertible preferred stock warrant liability, Shares															57,347
Issuance of common stock upon exercise of options for cash, Shares	22,307	22,307
Repurchase of unvested founders shares		-286,817
Vesting of restricted common stock issued to founders	10		10			10
Stock-based compensation expense	443		443			443
Net loss	-33,018				-33,018	-33,018
Ending Balances at Dec. 31, 2012													1,191		53,504
Ending Balances at Dec. 31, 2012	-45,503	1	453		-45,957	-45,503
Ending Balances, shares at Dec. 31, 2012													972,330		8,181,576
Ending Balances, shares at Dec. 31, 2012		4,834,467
Beginning Balances at Nov. 30, 2012
Issuance of common stock options in exchange for services															12,000
Ending Balances at Dec. 31, 2012													1,191		53,504
Ending Balances, shares at Dec. 31, 2012													972,330		8,181,576
Beginning Balances at Dec. 31, 2012	-45,503	1	453		-45,957	-45,503
Beginning Balances, Shares at Dec. 31, 2012		4,834,467
Issuance of common stock upon exercise of options for cash	6		6			6
Issuance of common stock upon exercise of options for cash, Shares	3,248	3,248
Vesting of restricted common stock issued to founders	10		10			10
Stock-based compensation expense	2,045		2,045			2,045
Net loss	-53,635				-53,635	-53,635
Ending Balances at Dec. 31, 2013	-97,077	1	2,514		-99,592	-97,077
Ending Balances, shares at Dec. 31, 2013	9,153,906												972,330		8,181,576
Ending Balances, shares at Dec. 31, 2013	4,837,715	4,837,715
Beginning Balances at Dec. 31, 2013													1,191		53,504
Beneficial conversion feature related to convertible notes issued in 2011/2013	-3,939		-3,939			-3,939
Issuance of convertible preferred stock for InteKrin acquisition															3,667
Issuance of convertible preferred stock for InteKrin acquisition, Shares															960,486
Issuance of convertible preferred stock net of issuance costs																	54,660
Issuance of convertible preferred stock net of issuance costs, Shares																	5,488,892
Issuance of convertible preferred stock value upon conversion of convertible promissory notes																	10,583
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares																	1,058,089
Issuance of convertible preferred stock in exchange for services															57		100
Issuance of convertible preferred stock in exchange for services, Shares															8,185		9,997
Issuance of convertible preferred stock upon exercise of warrants, including the reclassification of the associated convertible preferred stock warrant liability													1,004		39,277
Issuance of convertible preferred stock upon exercise of warrants, including the reclassification of the associated convertible preferred stock warrant liability, Shares													62,251		4,574,713
Issuance of common stock in connection with initial public offering								80,209			80,209	80,209
Issuance of common stock in connection with initial public offering, Shares									6,803,702
Conversion of convertible preferred stock and common stock warrants to common stock in connection with initial public offering								164,043	2		164,041	164,043		-2,195		-96,505		-65,343
Conversion of convertible preferred stock and common stock warrants to common stock in connection with initial public offering, Shares									21,316,519	491,580				-1,034,581		-13,724,960		-6,556,978
Issuance of common stock options in exchange for services	48		48			48
Issuance of common stock upon exercise of options for cash	55		55			55
Issuance of common stock upon exercise of options for cash, Shares	48,414	48,414
Repurchase of unvested founders shares, Value	-2		-2			-2
Repurchase of unvested founders shares		-239,952
Vesting of restricted common stock issued to founders	5		5			5
Stock-based compensation expense	11,117		11,117			11,117
Cumulative translation adjustment	-525			-525		-525
Distributions to non-controlling interest	-44						-44
Net loss	-87,133				-87,133	-87,133
Ending Balances at Dec. 31, 2014	$66,757	$3	$254,048	($525)	($186,725)	$66,801	($44)
Ending Balances, shares at Dec. 31, 2014	0												0		0
Ending Balances, shares at Dec. 31, 2014	33,257,978	33,257,978

Consolidated_Statements_of_Con1

Consolidated Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Parenthetical) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2012
IPO
Stock issuance/ offering costs	$11,641
Series B Convertible Preferred Stock
Issuance price per share of convertible preferred stock		$6.97
Stock issuance/ offering costs		3,562
Conversion price per share of convertible preferred stock		$6.97
Exchange price per share of convertible preferred stock for services		$6.97
Series C Convertible Preferred Stock
Issuance price per share of convertible preferred stock	$6
Stock issuance/ offering costs	$240
Conversion price per share of convertible preferred stock	$6
Exchange price per share of convertible preferred stock for services	$6

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($87,177,000)	($53,635,000)	($33,018,000)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	674,000	404,000	221,000
Remeasurement of contingent consideration	5,185,000
Remeasurement of convertible preferred stock warrant and embedded derivative liabilities	15,899,000	4,557,000	-639,000
Fair value of warrants in excess of debt proceeds recognized at issuance		3,669,000
Fair value of embedded derivative in excess of debt proceeds recognized at issuance		4,096,000
Preferred stock issued in exchange for services	147,000	7,579,000	7,956,000
Non-cash interest expense and amortization of debt discount	3,897,000	5,293,000	1,514,000
Gain on extinguishment of 2013 and 2011 Notes	-2,048,000		-6,369,000
Stock-based compensation expense	11,062,000	2,045,000	443,000
Changes in operating assets and liabilities:
Receivables from collaboration and license agreement	-2,139,000	-120,000	-158,000
Notes receivable	-1,815,000
Notes receivable from related parties	107,000	16,000	-5,000
Prepaid assets	-14,692,000	-3,284,000	-1,999,000
Other assets	-2,046,000	60,000	-50,000
Other assets - related party	-1,691,000
Other assets - non-current	-25,000	-21,000	207,000
Accounts payable	3,629,000	924,000	1,685,000
Accounts payable - related parties	1,637,000	-1,310,000	1,693,000
Accrued liabilities	3,949,000	2,847,000	2,162,000
Other liabilities	31,000	-2,000	14,000
Deferred revenue	19,848,000	34,749,000	8,101,000
Advance payments under license agreements with related party	1,192,000
Contingent liability to collaborator	20,150,000	7,500,000
Other liabilities, non-current	299,000	56,000	-9,000
Net cash (used in) provided by operating activities	-23,927,000	15,423,000	-18,251,000
Investing activities
Net cash acquired from acquisition of InteKrin Therapeutics, Inc.	2,334,000
Purchases of property and equipment	-2,849,000	-373,000	-1,783,000
Increase in restricted cash	-10,000		-40,000
Net cash used in investing activities	-525,000	-373,000	-1,823,000
Financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs	54,660,000		26,938,000
Proceeds from issuance of convertible notes		2,900,000
Proceeds from issuance of convertible notes - related parties		7,050,000
Proceeds from issuance of convertible preferred stock upon exercise of warrants	131,000
Proceeds from initial public offering, net of underwriters discounts and commissions	85,419,000
Payments of initial public offering costs	-4,307,000
Proceeds from issuances of common stock upon exercise of stock options	55,000	6,000
Repurchase of restricted common stock	-2,000
Net cash provided by financing activities	135,956,000	9,956,000	26,938,000
Effect of exchange rate changes in cash and cash equivalents	-666,000
Net increase in cash and cash equivalents	110,838,000	25,006,000	6,864,000
Cash and cash equivalents at beginning of period	39,554,000	14,548,000	7,684,000
Cash and cash equivalents at end of period	150,392,000	39,554,000	14,548,000
Supplemental disclosures of noncash investing and financing activities
Contingent consideration accrued in connection with acquisition	1,310,000
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise	40,150,000		400,000
Vesting of restricted common stock	5,000	10,000	10,000
Purchase of equipment in accounts payable	726,000	169,000
Initial public offering costs in accounts payable	855,000
Accrued expenses settled in common stock warrants	55,000
Accrued expenses settled in preferred stock	10,000
Issuance of convertible preferred stock in consideration for services			15,535,000
Reacquisition of beneficial conversion feature as a result of the conversion of 2011 Notes			10,631,000
Series B Convertible Preferred Stock
Supplemental disclosures of noncash investing and financing activities
Issuance of Series B Preferred stock for acquisition	3,667,000
Conversion of 2011/2013 Notes and accrued interest into convertible preferred stock			10,631,000
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise	39,300,000
Series C Convertible Preferred Stock
Supplemental disclosures of noncash investing and financing activities
Conversion of 2011/2013 Notes and accrued interest into convertible preferred stock	$10,583,000

Organization_and_Operations

Organization and Operations	12 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Operations	1	Organization and Operations
	Description of the Business
	Coherus BioSciences, Inc. (the “Company”, “Coherus”, “we”, “our” or “us”) was incorporated in the state of Delaware as BioGenerics, Inc. in September 2010 and changed its name to Coherus BioSciences, Inc. in April 2012. The Company is a late-stage clinical biologics platform company, focused on the global biosimilar market. The Company’s headquarters and laboratories are located in Redwood City, California and in Camarillo, California, respectively. The Company operates in one segment.
	The Company’s clinical stage pipeline consists of two anti-inflammatory agents targeting tumor necrosis factor, or TNF, and a long-acting form of granulocyte colony-stimulating factor, or G-CSF. The Company’s most clinically advanced anti-TNF product candidate, CHS-0214, is being developed as an etanercept (Enbrel) biosimilar that the Company has partnered with Baxter International Inc., Baxter Healthcare Corporation and Baxter Healthcare SA (collectively “Baxter”) and Daiichi Sankyo Company, Limited (“Daiichi Sankyo”) to develop and commercialize in key markets outside of the United States. The Company is currently enrolling two Phase 3 clinical trials with CHS-0214 to support the planned filing of a marketing application in Europe in 2016. The Company’s second anti-TNF product candidate, CHS-1420, is being developed as an adalimumab (Humira) biosimilar. This product successfully completed a pivotal Phase 1 PK study in August 2014 by meeting the primary study endpoint. The Company plans to initiate a Phase 3 trial during the first half of 2015 to support the planned filing of a marketing application in the United States in 2016 and the European Union, or E.U., in 2017. The Company’s long-acting G-CSF product candidate, CHS-1701, is being developed as a pegfilgrastim (Neulasta) biosimilar.
	Initial Public Offering
	On November 6, 2014, the Company’s registration statement on Form S-1 (File No. 333-198936) relating to its initial public offering (“IPO”) of its common stock was declared effective by the Securities and Exchange Commission (“SEC”) and the shares began trading on The NASDAQ Global Market on November 6, 2014. The price of the shares sold in the IPO was $13.50 per share. The IPO closed on November 12, 2014, pursuant to which the Company sold 6,803,702 shares of common stock, including the sale of 507,402 shares of common stock to the underwriters upon their partial exercise of their over-allotment option. The Company received total gross proceeds from the offering of $91.8 million, after deducting underwriting discounts and commissions of $6.4 million and offering expenses of $5.2 million, the net proceeds were $80.2 million. In connection with the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 21,316,519 shares of common stock, including 185,302 outstanding convertible preferred stock warrants were exercised, for cash or on a net basis. Also, all outstanding warrants for common stock were exercised, on a net basis, into 491,580 shares of common stock in connection with the IPO.
	Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on November 12, 2014, the number of shares of capital stock the Company is authorized to issue was increased to 300,000,000 shares of common stock and 5,000,000 shares of preferred stock. Both the common stock and preferred stock have a par value of $0.0001 per share.
	Need to Raise Additional Capital
	As of December 31, 2014, the Company had an accumulated deficit of $186.7 million and cash and cash equivalents of $150.4 million. The Company believes that its current available cash and cash equivalents together with the cash received from the IPO, will be sufficient to fund its planned expenditures and meet the Company’s obligations through at least the next twelve months. However, if the anticipated operating results are not achieved in future periods, the planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund the operations. The Company will need to raise additional funds in the future, however there can be no assurance that such efforts will be successful or that, in the event that they are successful, the terms and conditions of such financing will be favorable.

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2	Basis of Presentation and Summary of Significant Accounting Policies
	Basis of Consolidation
	The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). The accompanying consolidated financial statements include the accounts of Coherus and its wholly owned subsidiaries as of December 31, 2014: Coherus Intermediate Corp, InteKrin Therapeutics, Inc. (“InteKrin”), and its 82.5% majority owned subsidiary of InteKrin Russia. Unless otherwise specified, references to the Company are references to Coherus and its consolidated subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation.
	Reverse Stock Split
	In October 2014, the Company’s board of directors and its stockholders approved the filing of an amended and restated certificate of incorporation to effect a reverse split of the then outstanding shares of the Company’s preferred stock and common stock on a 1-for-1.667 basis (the “Reverse Stock Split”). All information in these financial statements related to the number of shares, price per share and per share amounts of stock, and shares issuable under stock options and warrants have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was effectuated on November 5, 2014. The Company filed an amended and restated certificate of incorporation in Delaware on November 5, 2014 that automatically effectuated the Reverse Stock Split without any further action required.
	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuations of the convertible preferred stock warrant liability and embedded derivative instruments, valuation of deferred tax assets, convertible preferred stock, clinical trial accruals, revenue recognition period, as well as certain accrued liabilities. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
	Foreign Currency
	The functional currency of InteKrin Russia, which the Company acquired in February 2014, is the Russian Ruble. Accordingly, the financial statements of this subsidiary are translated into U.S. dollars using appropriate exchange rates. Unrealized gains or losses on translation are recognized in accumulated other comprehensive loss in the condensed consolidated balance sheet.
	For the years ended December 31, 2014, 2013 and 2012, the foreign exchange gains and losses recorded in other income (expense), net in the consolidated statements of operations was a $671,000 gain, a $34,000 loss and $0, respectively.
	Segment Reporting
	The Company operates and manages its business as one reportable and operating segment, which is the business of developing and commercializing biosimilar products, and small molecules as part of the InteKrin acquisition (see Note 6). The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. Long-lived assets are primarily maintained in the United States of America.
	The following table summarizes revenue by geographic region:
			Year Ended December 31,
			2014			2013		2012
	United States		$	28,481		$	726	—
	Rest of world			2,625			2,025		1,899
	Total revenue		$	31,106		$	2,751	$	1,899
	Deferred Offering Costs
	Deferred offering costs, which primarily consisted of direct incremental legal and accounting fees relating to the IPO, were capitalized in other assets until the completion of the IPO. These deferred offering costs were reclassified to additional paid-in capital upon the closing of the IPO in November 2014. There were no deferred offering costs capitalized as of December 31, 2013.
	Cash and Cash Equivalents
	The Company considers all highly liquid investment with original maturities of 90 days or less at the date of purchase to be cash and cash equivalents.
	Restricted Cash
	Restricted cash consists of cash held in a money market account with a bank, and which is collateral against the Company’s corporate credit cards.
	Concentration of Credit Risk
	The Company’s financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank accounts which at times exceed federally insured limits. The Company attempts to minimize the risks related to cash and cash equivalents by investing in money markets with a broad and diverse range of financial instruments. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. The Company also maintains restricted cash in money market funds that invest primarily in U.S. Treasury securities. The Company has not recognized any losses from credit risks on such accounts during any of the periods presented. The Company believes it is not exposed to significant credit risk on its cash and money market funds.
	Customer Concentration
	Customers whose revenue accounted for 10% or more of total revenues were as follows:
			Year Ended December 31,
			2014		2013	2012
	Daiichi Sankyo - related party		*		74%	100%
	Baxter		92%		26%	—
	*	less than 10%
	Fair Value of Financial Instruments
	Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis.
	Property and Equipment
	Property and equipment are stated at cost less accumulated depreciation and amortization. Maintenance and repairs are charged to expense as incurred, and costs of improvements are capitalized. Depreciation and amortization is recognized using the straight-line method over the following estimated useful lives:
	Computer equipment and software		3 years
	Furniture and fixtures		5 years
	Machinery and equipment		5 years
	Leasehold improvements		Shorter of lease term or useful life
	Impairment of Long Lived Assets and Acquired Intangible Asset
	The Company reviews long-lived assets, including property and equipment, and indefinite-lived intangible, for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value.  As of December 31, 2014, there have been no such impairments.
	Acquired IPR&D represents the fair value assigned to research and development assets that have not reached technological feasibility.  The Company reviews amounts capitalized as acquired IPR&D for impairment at least annually, and whenever events or changes in circumstances indicate that the carrying value of the assets might not be recoverable. If the carrying value of the acquired IPR&D exceeds its fair value, then the intangible asset is written-down to its fair value. As of December 31, 2014, there have been no such impairments. Once the product candidate derived from the indefinite-lived intangible asset has been developed and commercialized, the useful life will be determined, and the carrying value of the finite-lived asset will be amortized prospectively over that estimated useful life. Alternatively, if the product candidate is abandoned, the carrying value of the intangible will be charged to research and development expense.
	Goodwill
	Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired. The Company tests goodwill for impairment at least annually or more frequently if events or changes in circumstances indicate that this asset may be impaired. The goodwill test is based on our single operating segment and reporting unit structure.
	The Company compares the fair value of its reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company would need to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of the reporting unit’s goodwill exceeds its implied fair value, then the Company would record an impairment loss equal to the difference. No goodwill impairment was identified through December 31, 2014.
	Convertible Preferred Stock
	The Company recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance. In the event of a change of control of the Company, proceeds received from the sale of such shares would have been distributed in accordance with the liquidation preferences set forth in the Company’s Amended and Restated Certificate of Incorporation unless the holders of convertible preferred stock have converted their shares of convertible preferred stock into shares of common stock. Therefore, convertible preferred stock was classified outside of stockholders’ equity (deficit) on the consolidated balance sheets as events triggering the liquidation preferences were not solely within the Company’s control. The Company elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. In November 2014, as a result of the Company’s IPO, all shares of convertible preferred stock were converted into shares of common stock on a one-for-one basis.
	Convertible Preferred Stock Warrant Liability
	The Company classified warrants exercisable for shares of the Company’s Series A and Series B convertible preferred stock as derivative liabilities and adjusted their carrying value to fair value at the end of each reporting period as long as such warrants were outstanding. At the end of each reporting period, changes in the fair value of the convertible preferred stock warrant liability during the period were recorded as a component of other income (expense), net, in the consolidated statements of operations.
	Derivative Liability
	The Company has a derivative liability related to the contingent consideration associated with the acquisition of InteKrin. There are two contingent payments payable upon the achievement of certain events: (i) the completion of the first dosing of a human subject in the first Phase 2 clinical trial for InteKrin, (“Earn-Out Payment”) and (ii) upon the execution of any license, sublicense, development, collaboration, joint venture, partnering or similar agreement between the Company and the third party (“Compound Transaction Payment”). The derivative related to the contingent consideration is accounted for as a liability and remeasured to fair value as of each balance sheet date and the related remeasurement adjustment is recognized as other income (expense), net in the consolidated statements of operations. The Company determined the fair value of the two contingent consideration scenarios (the Earn-Out Payment and the Compound Transaction Payment) using a probability-weighted discounted cash flow approach. A probability-weighted value was determined by summing the probability of achieving a contingent payment threshold by the respective contingent payments. The expected cash flows were discounted at a rate selected to capture the risk of achieving the contingent payment thresholds and earning the contingent payment. This risk is comprised of InteKrin’s continued development, a specific risk factor associated with meeting the contingent consideration threshold and related payout, and counterparty risk associated with the payment of the contingent consideration.
	Embedded Derivative Liability
	The Company recorded derivative instruments related to redemption features embedded within the convertible notes when such notes were outstanding. The embedded derivatives were accounted for as a liability and were remeasured to fair value as of each balance sheet date when such notes were outstanding, with the related remeasurement adjustment being recognized as a component of other income (expense), net in the consolidated statements of operations.
	Accrued Research and Development Expenses
	Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the actual costs through monitoring patient enrollment and discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
	Revenue Recognition
	The Company recognizes revenue when persuasive evidence of an arrangement exists; transfer of technology has been completed, services have been performed or products have been delivered; the fee is fixed and determinable; and collection is reasonably assured.
	The Company enters into collaboration and license agreements for the development and commercialization of biosimilar products. The Company’s performance obligations under the terms of these agreements may include (i) transfer of intellectual property rights (licenses), (ii) providing research and development services, (iii) the manufacture of drug materials for development purposes and (iv) participation on certain committees with the collaborators. Payments to the Company under these agreements may include nonrefundable upfront license fees, payments for research and development services, payments for the manufacture of drug materials, payments based upon the achievement of defined collaboration objectives and royalties on product sales. Under these agreements, the Company may convey the right to sell products resulting from the collaborative efforts of the parties in specific geographic territories.
	For revenue agreements with multiple elements, the Company identifies the deliverables included within the agreement and evaluates which deliverables may represent separate units of accounting based on the achievement of certain criteria, including whether the delivered element has stand-alone value to the collaborator. Deliverables under the arrangement are a separate unit of accounting if (i) the delivered item has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item and delivery or performance of the undelivered items are considered probable and substantially within the Company’s control.
	The Company determines how to allocate arrangement consideration to identified units of accounting based on the selling price hierarchy provided under the relevant guidance. The selling price used for each unit of accounting is based on vendor-specific objective evidence, if available, third party evidence if vendor-specific objective evidence is not available or estimated selling price if neither vendor-specific nor third-party evidence is available. Management may be required to exercise considerable judgment in determining whether a deliverable is a separate unit of accounting and in estimating the selling prices of identified units of accounting under its agreements.
	Upfront payments received in connection with licenses of the Company’s technology rights are deferred if facts and circumstances dictate that the license does not have stand-alone value. Such payments are recognized as license revenue over the estimated period of performance that is generally consistent with the terms of the research and development obligations contained in the specific collaboration and license agreement. The Company regularly reviews the estimated period of performance based on the progress made under each arrangement. Amounts received as funding of research and development activities are recognized as revenue if the collaboration arrangement involves the sale of the Company’s research or development services. However, such funding is recognized as a reduction in research and development expense when the Company engages in a research and development project jointly with another entity, with both entities participating in project activities and sharing costs and potential benefits of the arrangement.
	Payments that are contingent upon the achievement of a substantive milestone are recognized in their entirety in the period in which the milestone is achieved, assuming all other revenue recognition criteria are met. Milestones are defined as an event that can only be achieved based on the Company’s performance and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones under accounting guidance. The Company’s evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the Company’s performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
Other contingent payments in which a portion of the payment is refundable or adjusts based on future performance or non-performance (e.g., through a penalty or claw-back provision) are not considered to relate solely to the Company’s past performance, and therefore, not considered substantive. Non-substantive contingent payments are classified as deferred revenue if they are ultimately expected to result in revenue recognition. The Company recognizes non-substantive contingent payments over the remaining estimated period of performance once the specific objective is achieved. Any portion of the non-substantive contingent payments which may be required to be refunded to the collaborator are not included in deferred revenue and instead are reflected as contingent liability to collaborator on the consolidated balance sheets.
Contingent payments associated with the achievement of specific objectives in certain contracts that are not considered substantive because the Company does not contribute effort to the achievement of such milestones are recognized as revenue upon achievement of the objective, as long as there are no undelivered elements remaining and no continuing performance obligations by the Company, assuming all other revenue recognition criteria are met.
The government contract with the Russian government is an agreement that provides the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from the government contract is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the funds received are not refundable and applicable conditions under the government contract have been met. Funds received in advance are recorded as deferred revenue.
Research and Development Expenses
Research and development costs are charged to expenses as incurred. Research and development expenses include, among other costs, salaries and other personnel-related costs, consultant fees, preclinical costs, cost to manufacture drug candidates and clinical supplies, laboratory supplies costs and facility-related costs. Costs incurred under agreements with third parties are charged to expense as incurred in accordance with the specific contractual performance terms of such agreements. Costs of third parties include costs associated with preclinical and clinical support activities. In certain cases, amounts received as reimbursement of research and development activities from the Company’s collaborators are recognized as a reduction in research and development expense when the Company engages in a research and development project jointly with another party, with both parties incurring costs while actively participating in project activities and both parties sharing costs and potential benefits of the arrangement. Costs incurred under the arrangements where the Company provides research services approximate the amount of revenues recorded. Advance payments for goods or services to be received in the future to be utilized in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are received.
Stock-Based Compensation
The Company measures the cost of equity-based service awards based on the grant-date fair value of the award, and recognizes the cost of such awards straight-line over the vesting period. Because non-cash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates.
The Company accounts for equity instruments issued to nonemployees using the fair value approach. These equity instruments consist of stock options and restricted common stock, which are valued using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized as the equity instruments are earned. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest.
The Company utilizes the Black-Scholes option-pricing model for estimating fair value of its stock options and restricted stock granted. Option valuation models, including the Black-Scholes option-pricing model, require the input of highly subjective assumptions, and changes in the assumptions used can materially affect the grant-date fair value of an award. These assumptions include the risk-free rate of interest, expected dividend yield, expected volatility, the expected life of the award, and estimated forfeitures.
Income Taxes
The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.
The Company recognizes uncertain income tax positions at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. The Company does not expect its unrecognized tax benefits to change significantly over the next twelve months.
The Company’s policy is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had accrued no amounts for interest and penalties related to income tax matters in the Company’s consolidated balance sheets at December 31, 2014 and 2013.
Comprehensive Loss
Comprehensive loss is composed of two components: net loss and other comprehensive income (loss). Other comprehensive income (loss) refers to gains and losses that under U.S. GAAP are recorded as an element of stockholders’ equity (deficit), but are excluded from net loss. The Company’s other comprehensive loss included foreign currency translation adjustments for the year ended December 31, 2014.
Net Loss per Share Attributable to Coherus
Basic net loss per share attributable to Coherus is calculated by dividing the net loss attributable to Coherus by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive common shares. Since the Company was in a loss position for all periods presented, basic net loss per share attributable to Coherus is the same as diluted net loss per share attributable to Coherus as the inclusion of all potential dilutive common shares would have been anti-dilutive. Shares of founders’ common stock subject to repurchase are excluded from the calculation of weighted average shares as the vesting of such shares is contingent upon continued services being rendered by such holders.
Recent Accounting Pronouncements
In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which converges the FASB and the International Accounting Standards Board standards on revenue recognition. Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variable consideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. This guidance is effective for the fiscal years and interim reporting periods beginning after December 15, 2016, at which time the Company may adopt the new standard under the full retrospective method or the modified retrospective method. Early adoption is not permitted. The Company is currently evaluating the impact that the adoption of ASU 2014-09 will have on its consolidated financial statements and related disclosures.
In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. In doing so, companies will have reduced diversity in the timing and content of footnote disclosures than under today’s guidance. ASU 2014-15 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2014-15 will have on its consolidated financial statements and related disclosures.
The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or no material effect is expected on the consolidated financial statements as a result of future adoption.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	3	Fair Value Measurements
	Financial assets and liabilities are recorded at fair value. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts payable and other current liabilities approximate their fair value due to their short maturities. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The accounting guidance describes a fair value hierarchy based on three levels of inputs that may be used to measure fair value, of which the first two are considered observable and the last is considered unobservable. These levels of inputs are the following:
	Level 1 — Quoted prices in active markets for identical assets or liabilities.
	Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	The Company’s financial instruments consist of Level 1 assets and Level 3 liabilities. Where quoted prices are available in an active market, securities are classified as Level 1. Level 1 assets consist of highly liquid money market funds that are included in cash and cash equivalents, and restricted cash. There were no unrealized gains and losses in the Company’s investments in these money market funds.
	In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. Level 3 liabilities consist of the convertible preferred stock warrant liability, embedded derivative instruments and contingent consideration.
	Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements are as follows (in thousands):
			Fair Value Measurements
			31-Dec-14
			Total			Level 1		Level 2		Level 3
	Assets:
	Money market funds		$	147,952		$	147,952	$	—	$	—
	Restricted cash (money market funds)			60			60		—		—
	Total financial assets		$	148,012		$	148,012	$	—	$	—
	Liabilities:
	Contingent consideration		$	6,495		$	—	$	—	$	6,495
			Fair Value Measurements
			31-Dec-13
			Total			Level 1		Level 2		Level 3
	Assets:
	Restricted cash (money market funds)		$	50		$	50	$	—	$	—
	Liabilities:
	Convertible preferred stock warrant liability		$	24,251		$	—	$	—	$	24,251
	There were no transfers between Level 1 and Level 3 during the periods presented.
	The Company issued convertible notes in 2011 and 2013 (see Note 7). In connection with the convertible notes, the Company agreed to issue warrants to purchase shares of its preferred stock, the 2011 Warrants B and 2013 Warrants. The convertible notes also contained redemption features which were determined to be embedded derivatives requiring fair value accounting. The aggregate principal under the convertible notes issued in 2013 of $10.0 million was less than the initial fair value of the warrants and embedded derivatives of $13.6 million and $4.1 million, respectively, therefore, the entire loan principal balance of $10.0 million was offset by only a portion of the debt discount, as the debt could not be reduced to a carrying value amount which was less than zero. The difference of $3.6 million and $4.1 million associated with the convertible preferred stock warrant liability and embedded derivatives, respectively, was immediately charged to other income (expense), net, in the consolidated statements of operations (see Note 7 and Note 8 for further detail regarding the determination and valuation of the embedded derivatives and convertible preferred stock warrant liability, respectively).
	The fair values of the convertible preferred stock warrant liability and embedded derivatives were based on the following assumptions at the respective issuance dates and as of December 31, 2013.  These instruments were not outstanding as of December 31, 2014:
			Jul-13		August and	December 31,
			Issuance		Sep-13	2013
					Issuance
	Discount rate		30%		30%	30%
	Weighted-average scenario probabilities:
	New equity financing		25%		65%	63%
	New equity financing at lower valuation then previous financing		5%		5%	7%
	Initial public offering		5%		5%	10%
	Change of control		25%		5%	—
	Maturity		40%		20%	20%
	Preferred Stock Warrant Liability
	The fair value of the convertible preferred stock warrants was determined based on Level 3 inputs. The Company determined the fair value of the warrants by allocating the Company’s equity value using a combination of the Probability-Weighted Expected Return Method (“PWERM”) and the Option-Pricing Method (“OPM”). The Company’s equity value was allocated among preferred stock, common stock, warrants and stock options expected to be outstanding at the expected future liquidity events based on the rights and preferences of each class. The OPM considers a distribution of future equity values based on the time to liquidity and the expected volatility in the total equity value. Inputs to the OPM include assumptions related to the fair value of the shares, the exercise price, expected volatility, expected term, risk-free interest rate, and the expected dividend yield. The estimated expected volatility was based on the volatility of common stock of a group of comparable, publicly-traded companies. The estimated expected term was based on the estimated time to liquidity event. The risk-free interest rate was based on the U.S. Treasury yield for a term consistent with the estimated expected term. The significant unobservable input used in the fair value measurement of the convertible preferred stock warrant liability is the fair value of the underlying preferred stock at the valuation remeasurement date.
	The PWERM considers specific future equity values based on knowledge of a potential transaction or IPO. The range of future equity values is probability-weighted and discounted at a risk-adjusted rate. Some of the valuations applied a combination of the two allocation methods to capture the fair value of the warrants. During 2014, the warrants were valued using the PWERM exclusively based on the expectation for an IPO in November 2014. The size of the IPO and the implied pre-money total equity values were used to support the warrants value. Generally, increases (decreases) in the fair value of the underlying preferred stock would result in a directionally similar impact to the fair value measurement. The change in the fair value of the convertible preferred stock warrant liability is recognized in other expense, net within the consolidated statement of operations.
	During 2014, all warrants to purchase convertible preferred stock were exercised, for cash or on a net basis, and the fair value of the warrants on the day of exercise was recorded to the respective series of convertible preferred stock reducing the preferred stock warrant liability to zero by December 31, 2014.
	The following table sets forth a summary of the changes in the estimated fair value of the convertible preferred stock warrants (in thousands):
			December 31,
			2014			2013
	Balance, beginning of year		$	24,251		$	1,738
	Warrants issued in connection with notes payable		—				9,950
	Initial fair value of the warrants issued in excess of debt		—				3,669
	proceeds recognized in other income (expense), net
	Warrants exercised			(40,150	)	—
	Change in fair value of convertible preferred stock warrant liability			15,899			8,894
	Balance, end of year		$	—		$	24,251
	Contingent Consideration
	As part of the InteKrin acquisition, the Company recognized contingent consideration associated with potential payments to be made to the former InteKrin stockholders upon the achievement of certain events specified in the agreements (see Note 6). This fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement within the fair value hierarchy. The Company valued the two contingent consideration scenarios (the Earn-Out Payment and the Compound Transaction Payment) using a probability-weighted discounted cash flow approach. A probability of reaching each contingent consideration threshold was estimated by Company’s management. As of December 31, 2014, the Earn-Out Payment was expected to occur in January 2015 with a 98% probability of occurrence. As part of the analysis, a 25% risk-adjusted discount rate was used to measure a present value. A separate credit spread was not applied to the Earn-Out Payment fair value since the consideration is to be made in common stock shares. The size of the contingent consideration is a fixed number of common stock shares, but the value fluctuates with the value of a common stock share. The Compound Transaction applied the same 25% risk-adjusted discount rate and also captured an additional 6% credit spread for counterparty credit risk given the cash payment. The Company’s management estimates of probability of occurrence and timing were used to formulate an expected cash flow. The size of the consideration is tiered based on the size of a license or similar agreement with a third party and the timing of such agreement. The change in the fair value of the contingent consideration liability is recognized in other expense, net within the consolidated statement of operations.
	The following table sets forth a summary of changes in the estimated fair value of the contingent consideration (in thousands):
	Balance as of February 12, 2014 (acquisition date)		$	1,310
	Change in fair value of the contingent consideration liability			5,185
	Balance as of December 31, 2014		$	6,495
	Embedded Derivatives in Convertible Notes
	The convertible notes issued in 2011 and 2013 had redemption features which were determined to be embedded derivatives requiring bifurcation and separate accounting. The fair value of the derivatives was determined based on an income approach that identified the cash flows using a “with-and-without” valuation methodology. The inputs used to determine the estimated fair value of the derivative instruments are based largely on the probability of an underlying event triggering the embedded derivative occurring and the timing of such event. The only derivative that had any significant value was the derivative liability corresponding to the redemption feature in the 2013 Notes associated with the option to receive a cash payment equal to 400% of outstanding principal plus accrued interest upon a change of control prior to a qualified licensing transaction (“QLT”).
	The Company periodically remeasured the derivative instrument to fair value as of each balance sheet date. In December 2013, following the receipt of the upfront license payment from Baxter license agreement (see Note 5), the Company achieved the QLT. As a result, upon a change of control, the redemption feature related to the holders’ option to receive a cash payment in lieu of conversion into Series B convertible preferred stock was reduced from 400% to 100% of the outstanding principal, plus accrued interest. As such, the fair value of the derivative liability was reduced to zero at the time of the achievement of the QLT in December 2013.
	The following table sets forth a summary of the changes in the estimated fair value of the derivative instrument (in thousands):
			December 31,
			2013
	Balance, beginning of year		$	—
Initial fair value of the embedded derivative issued in excess			4,096
of debt proceeds recognized in other income (expense), net
Change in fair value of embedded derivative			(4,096	)
Balance, end of year		$	—

Balance_Sheet_Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	4	Balance Sheet Components
	Prepaid Assets
	Prepaid assets are as follows (in thousands):
			December 31,			December 31,
			2014			2013
	Prepaid clinical, material, manufacturing and other - related parties		$	5,990		$	3,177
	Prepaid clinical, material and  manufacturing			12,149			1,758
	Prepaid other			2,346			753
	Prepaid assets		$	20,485		$	5,688
	Property and Equipment, Net
	Property and equipment, net are as follows (in thousands):
			December 31,			December 31,
			2014			2013
	Machinery and equipment		$	4,317		$	2,051
	Computer equipment and software			286			79
	Furniture and fixtures			288			147
	Leasehold improvements			399			91
	Construction in progress			474			—
	Total property and equipment			5,764			2,368
	Accumulated depreciation and amortization			(1,292	)		(625	)
	Property and equipment, net		$	4,472		$	1,743
	Depreciation expense was $674,000, $404,000 and $221,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	In June 2013, as part of a clinical manufacturing service agreement, the Company granted a first priority security interest to the Company’s property and equipment located in Camarillo, California to Cook Pharmica LLC (“Cook”), a CMO. In addition, during July 2013 and September 2013, the Company entered into the Bridge Loans (see Note 7), which were collateralized by a security interest in all of the Company’s assets, tangible and intangible, subject to the prior security interest held by Cook on the Company’s property and equipment located in Camarillo, California. Upon the issuance of Series C convertible preferred stock in May 2014, all security interests to the Company’s assets, tangible and intangible were released.
	Accrued Liabilities
	Accrued liabilities are as follows (in thousands):
			December 31,			December 31,
			2014			2013
	Accrued clinical, manufacturing and other - related parties		$	2,997		$	2,792
	Accrued compensation			3,435			1,549
	Accrued professional and consulting fees			252			995
	Accrued other			4,547			1,922
	Accrued liabilities		$	11,231		$	7,258

Collaboration_and_License_Agre

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2014
Collaboration And License Agreements [Abstract]
Collaborative and License Agreements	5	Collaboration and License Agreements
	The Company recognized revenue related to the collaboration and license agreements for the periods presented as follows (in thousands):
			Year Ended December 31,
			2014		2013		2012
	Daiichi Sankyo - related party		$	1,893	$	2,025	$	1,899
	Baxter			28,481		726		—
	Total collaboration and license revenue		$	30,374	$	2,751	$	1,899
	Daiichi Sankyo
	In January 2012, the Company entered into a license agreement with Daiichi Sankyo, under which the Company granted certain licenses to Daiichi Sankyo to develop and commercialize biosimilar forms of etanercept and rituximab in Japan, Taiwan, and South Korea with an option to develop in China. Under the terms of the agreement, the Company will be responsible for the manufacturing and supply of the products during the development activities and Daiichi Sankyo will conduct the development, regulatory approval filings, and commercialization activities of the biosimilar form of etanercept and rituximab products in Japan. Once the biosimilar forms of etanercept and rituximab are commercialized, the Company is entitled to royalties based on net sales by Daiichi Sankyo on a product-by-product basis in the licensed territories ranging from the low double digits to high teens, on a product-by-product basis. If the Company is manufacturing product, the Company is eligible to receive an incremental royalty reflecting the manufacturing costs for each licensed product which, when combined with the base royalty, will result in royalties equal to a percentage of net sales of licensed products ranging from the low to high-twenties, on a product-by-product basis.
	Upon execution of the agreement, Daiichi Sankyo paid a non-refundable, upfront license fee of $10.0 million and purchased 2,867,426 shares of Series B convertible preferred stock at a price of $6.9749 per share, or $18.1 million in net cash proceeds. The Company concluded that there was no premium or discount associated with the purchase of the Series B convertible preferred stock since Daiichi Sankyo paid the same price paid by other investors at the close of the Series B convertible preferred stock offering. As such the Company recorded the $18.1 million as a convertible preferred stock transaction separate from the license agreement. The agreement has an initial term of ten years and contains provisions allowing Daiichi Sankyo to renew the agreement for an additional three years with respect to particular countries. Daiichi Sankyo also has the right to terminate the agreement, in its entirety or on a country-by country basis, at any time if the development and/or commercialization is deemed to not be commercially viable, there are material safety, efficacy or patient tolerability issues that cannot be remedied or overcome, or during the opt-out window after the achievement of specified objectives in the agreement. In May 2012, Daiichi Sankyo opted out of the development and commercialization of etanercept in Taiwan and South Korea, and in August 2012, Daiichi Sankyo chose not to exercise their option with respect to the development and commercialization of etanercept and rituximab in China.
	The Company identified the following deliverables under the agreement: (1) the transfer of intellectual property rights (license), and (2) the manufacture of drug materials for clinical development purposes. The Company considered the provisions of the multiple-element arrangement guidance in determining how to recognize the total consideration of the agreement. The Company has concluded that the license is not a separate unit of accounting because Daiichi Sankyo cannot obtain benefit from the use of the license rights for their intended purpose without the products manufactured by the Company. Daiichi Sankyo must rely upon the Company to manufacture and supply the products necessary for Daiichi Sankyo’s development because the related manufacturing know-how specific to the products is proprietary to the Company and Daiichi Sankyo does not have the right to manufacture the licensed product. The Company determined that neither of the deliverables have standalone value and, therefore, the deliverables are accounted for as a single unit of accounting with the upfront fee recognized as revenue on a straight-line basis over its estimated period of performance of approximately three years. The Company determined that there is no other method that is more appropriate than the straight-line method of revenue recognition for this agreement given there is no discernable pattern of its performance under the arrangement. The Company regularly evaluates the reasonableness of the estimated period of performance and revises the amortization of deferred revenue as deemed appropriate on a prospective basis.  On September 30, 2014 and December 31, 2014, the Company revised the period of performance extending the period of performance for two quarters and one quarter, respectively.
	In June 2013, the Company and Daiichi entered into a Memorandum of Understanding No. 1 (the “MOU 1”) in which both parties agreed to cooperate and share costs to conduct a global Phase 1 study of a biosimilar form of etanercept. This program was not originally contemplated in the license agreement. Under the MOU 1, the Company will gather all clinical data, format it into a case study report, and conduct the final analysis. The Company will transfer the clinical data and other regulatory approval application documents for the product and post marketing to Daiichi Sankyo within 90 days after such documents are finalized. Under the MOU 1, Daiichi’s Sankyo’s overall cost sharing responsibility include (i) 33% of the total budgeted cost and (ii) 100% of the cost of the comparator drug (Enbrel) used for the Japanese volunteers. The amounts received from Daiichi Sankyo under this cost sharing responsibility are recognized as a reduction in research and development expense as the Company engages in a research and development project jointly with Daiichi Sankyo, with both parties incurring costs while actively participating in development activities and both parties sharing costs and potential benefits of the arrangement. The Company accounted for the MOU 1 as a separate arrangement which was not deemed to be a material modification of the original license agreement with Daiichi Sankyo.
	In January 2014, the Company and Daiichi Sankyo entered into the Memorandum of Understanding No. 2 (the “MOU 2”) in which both parties agreed to cooperate to conduct a global Phase 3 clinical trial in rheumatoid arthritis and that Daiichi Sankyo will be responsible for a minimum of 20% of the cost of the clinical trial. Also, both parties entered into a clinical supply agreement contemporaneously with the MOU 2 in which the Company will supply finished study drug and study comparator drug for Daiichi Sankyo’s use in the Japanese portion of the product’s clinical trial. Daiichi Sankyo reimburses these research and development costs in quarterly advance payments, for which the Company recorded $1.2 million as advance payments under license agreement in the consolidated balance sheet as of December 31, 2014. The Company will recognize the advance payment as a reduction in the research and development expense when the research and development activity has been performed.
	As of December 31, 2014, $4.3 million of revenue was deferred under all arrangement with Daiichi Sankyo, of which $1.6 million was included in current liabilities and $2.7 million was included in non-current liabilities in the consolidated balance sheet. As of December 31, 2013, $6.1 million of revenue was deferred under all arrangements with Daiichi Sankyo, of which $2.0 million was included in current liabilities and $4.1 million was included in non-current liabilities in the consolidated balance sheet.
	The Company recognized in its consolidated statements of operations a reduction of research and development expense related to the costs reimbursed by Daiichi Sankyo of $7.1 million, $1.3 million and $158,000  for the years ended December 31, 2014, 2013 and 2012, respectively.
	Baxter
	In August 2013, the Company entered into a license agreement with Baxter to develop and commercialize an etanercept biosimilar molecule, CHS-0214, worldwide, excluding the United States, Japan, Taiwan, South Korea, China and most of the Caribbean and South American nations. The agreement allowed for the development and commercialization of an alternative biosimilar to etanercept, and the expansion of the collaboration to include another product which lapsed in December 2013.
	Under the terms of the agreement, the Company will conduct the development and the regulatory activities, and Baxter will conduct the commercialization of the etanercept biosimilar product. In consideration of the exclusive, royalty-bearing license to develop, commercialize and use the etanercept biosimilar product, Baxter made an upfront payment of $30.0 million to the Company. Additionally, the Company is eligible to receive up to $216.0 million in contingent payments composed of $96.0 million in clinical development payments and up to $120.0 million in regulatory milestone payments. If the cumulative development costs exceed the cumulative contingent payments, Baxter will reimburse the Company for the excess cost as set forth in the agreement up to predetermined limits. Once the etanercept biosimilar product is commercialized, the Company is entitled to tiered royalties, based on the manufacturing cost as a percentage of net sales of licensed products, ranging from the mid-single digits to the high teens on a country-by-country basis. These royalties are subject to certain offsets and reductions.
	The agreement has an initial term of ten years and contains provisions allowing Baxter to renew the agreement for another three years on a country-by-country basis. Baxter also has the right to terminate the agreement, in its entirety or on a country-by country basis, at any time if the development and/or commercialization is deemed to not be commercially viable, there are material safety, efficacy or patient tolerability issues that cannot be remedied or overcome, if aggregate expenses exceed certain thresholds or after the first commercial sale upon 18 month prior written notice.
	The Company identified the following deliverables under the license agreement with Baxter: 1) the transfer of intellectual property rights (license), (2) the obligation to provide research and development services including the manufacturing and supply of clinical product, and (3) the obligation to participate on various committees.
	The Company considered the provisions of the multiple-element arrangement guidance in determining how to recognize the total consideration of the agreement. The Company determined that the license does not have standalone value to Baxter without the Company’s technical expertise as it relates to the development of the product candidate and committee participation. Additionally, the license to Baxter does not include the right to manufacture, or have manufactured the product during the development stage, or to conduct any process development activities. Therefore, the Company concluded that these deliverables represent a single unit of accounting under the multiple-element arrangement guidance.
	The upfront payment of $30.0 million and clinical development payments of up to $96.0 million include $56.0 million of contingent payments that are intended to cover development related expenses incurred by the Company, but potentially reimbursable, in part, to Baxter under certain limited circumstances. The Company concluded that the contingent payments that contain potentially reimbursable amounts to Baxter are not substantive milestones under the relevant accounting guidance, since the guidance does not allow the substantive milestone components of a payment to be bifurcated from non-substantive milestone components. The amounts that are contingent payments also contain a claw-back feature that, in the event that the Company commercializes the etanercept biosimilar molecule in the U.S. without Baxter, fifty percent (50%) of those contingent payments are refundable to Baxter. Therefore, the Company will record the portion of the non-substantive contingent payment that contains the claw-back feature as a liability for the potential reimbursement of such funds to Baxter until the earlier of: (1) expiration or termination of the license agreement, which is ten years, or (2) the determination of the party to commercialize the molecule in the U.S. These amounts are included in the contingent liability to collaborator on the consolidated balance sheets. The portion of the non-substantive milestone payment that does not contain the claw-back feature will be recorded as deferred revenue and recognized as license revenue on a straight-line basis over the remaining estimated performance period of approximately three years. The Company determined that there is no other method that is more appropriate than the straight-line method of revenue recognition for this agreement given there is no discernable pattern of performance under the arrangement. The Company regularly evaluates the reasonableness of the estimated period of performance and revises the amortization of deferred revenue as deemed appropriate on a prospective basis.  On September 30, 2014 and December 31, 2014, the Company revised the period of performance extending the period of performance for two quarters and one quarter, respectively.
	The $120.0 million of regulatory milestone payments are considered substantive as the achievement is subject to the significant uncertainty as to the outcome of the development efforts, by the Company, over an extended period of time, and the Company’s substantive performance obligation under the license agreement which includes efforts associated with the clinical trials and filing and approval of drug applications by regulatory authorities in various countries. Therefore, the Company will recognize revenue associated with these respective contingent payments when each of the specific events is achieved.
	In February 2014, the agreement was amended to increase the payment by $5.3 million therefore the Company is eligible to receive up to $221.3 million in contingent payments comprised of $101.3 million in clinical development payments, including $71.3 million of contingent payments, and up to $120.0 million in regulatory milestone payments.
	As of December 31, 2014, $58.4 million of revenue was deferred under the arrangements with Baxter, of which $21.2 million was included in current liabilities and $37.2 million was included in non-current liabilities in the consolidated balance sheet. As of December 31, 2014, $27.7 million was recorded as contingent liability to collaborator due to the potential refund of such amount to Baxter in the future. Additionally in 2014, the Company received $10.0 million for the achievement of a substantive milestone pursuant to the license agreement and accordingly recognized the entire amount as collaboration and license revenue in its consolidated statements of operations in the third quarter of 2014.
	As of December 31, 2013, $36.8 million of revenue was deferred under the arrangements with Baxter, of which $12.3 million was included in current liabilities and $24.5 million was included in non-current liabilities in the consolidated balance sheet. As of December 31, 2013, $7.5 million was recorded as contingent liability to collaborator in the consolidated balance sheet due to the potential refund to Baxter.

Acquisition_of_InteKrin_Therap

Acquisition of InteKrin Therapeutics, Inc.	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisition of InteKrin Therapeutics, Inc.	6	Acquisition of InteKrin Therapeutics, Inc.
	On January 8, 2014, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) to acquire all of the outstanding shares of InteKrin and its 82.5% majority owned subsidiary, InteKrin Russia. On February 12, 2014, the Company completed the acquisition of InteKrin (the “Merger”) for total consideration of $5.0 million.
	Prior to the Merger, InteKrin was a privately held, clinical-stage biopharmaceutical company focused on the development and commercialization of novel drugs for the treatment of immune diseases such as multiple sclerosis. InteKrin’s primary product candidate is INT-131, which is in the clinical stage of development. Although INT-131 is a small molecule and not a protein, its therapeutic focus area was complementary to the Company’s emerging multiple sclerosis biosimilar product pipeline which consists of broader level, central nervous system anti-inflammatory drug candidates. This in turn was complementary to the Company’s systemic focus on anti-inflammatory drug candidates with the anti-tumor necrosis factor (TNF) portfolio composed of etanercept and adalimumab biosimilars. Additionally, the acquisition of InteKrin was a strategic transaction to obtain funding from new investors.
	The Company accounted for the InteKrin acquisition as the purchase of a business. The Company expensed the related acquisition costs, consisting primarily of legal expenses in the amount of $134,000. These legal expenses are recorded in general and administrative expense in the consolidated statement of operations for the year ended December 31, 2014. The total consideration of $5.0 million consists of: (a) issuance of 716,645 shares of Series B preferred stock with a fair value of $2.7 million, (b) assumption of InteKrin’s convertible promissory note payable to an InteKrin stockholder, which was concurrently paid off by issuing 243,841 shares of the Company’s Series B convertible preferred stock with a fair value of $1.0 million (c) cash payment of $1,485, and (d) contingent consideration of $1.3 million. The Company determined the fair value of the Series B convertible preferred stock of $3.8174 per share using the PWERM. The non-controlling interest was not deemed to be significant at acquisition.
	Pro forma results of operations for this acquisition have not been presented as such results are not material to the Company’s results of operations for the years ended December 31, 2014 and 2013.
	The following table summarizes the original fair value of the assets acquired and liabilities assumed (in thousands):
	Cash		$	2,335
	Prepaid and other assets			107
	Accounts payable and other current liabilities			(1,027	)
	In-process research and development			2,620
	Goodwill			943
	Total consideration		$	4,978
	In connection with the acquisition of InteKrin, the Company recorded a deferred tax liability related to the acquired in-process research and development. This deferred tax liability represents a new source of future taxable income, which required the release of a portion of InteKrin’s deferred tax asset valuation allowance equal to the deferred tax liability recorded. The deferred tax asset and liability are both classified as long term for purposes of the balance sheet presentation.
	Intangible Asset — In-process Research and Development
	The in-process research and development (“IPR&D”) consists of InteKrin’s INT-131. The Company determined the fair value of the IPR&D based on the cost to recreate the asset to its current stage as the fair value is not determinable as a result of the lack of financial projections for this asset due to its early development stage. By applying this method, management estimated that $2.6 million of the acquisition consideration represents the fair value of the IPR&D. The IPR&D acquired through the InteKrin acquisition is treated as an indefinite-lived intangible asset and an annual impairment review will be performed by management. As of December 31, 2014, there have no such impairments.  Once this product has been developed and commercialized, the useful life will be determined, and the carrying value of the finite-lived asset will be amortized prospectively over that estimated useful life. Alternatively, if the INT-131 product is abandoned, the carrying value of the IPR&D will be charged to research and development expense.
	Contingent Consideration
	The contingent consideration is made up of two potential payments as discussed below.
	Contingent Consideration — Earn-out Payment: Upon completion of the first dosing of a human subject in the first Phase 2 clinical trial for InteKrin, InteKrin’s stockholders can earn a minimal cash payment and 358,384 shares of the Company’s Series B convertible preferred stock upon the successful achievement of this objective. At the acquisition date, the Company expected the first dosing to be completed in September 2014 and assigned a 75% success probability to the achievement of this event. As such, at the acquisition date, the fair value of the contingent consideration related to this earn-out payment was determined to be $0.8 million. As of the consummation of the IPO in November 2014, any such contingent consideration will be paid, if at all, by issuing shares of common stock rather than shares of Series B convertible preferred stock.
	Contingent Consideration — Compound Transaction Payment: Upon the execution of any license, sublicense, development, collaboration, joint venture, partnering or similar agreement between the Company and a third-party or any agreement between the Company and such third-party to sell all of the assets related to the acquired InteKrin compound to such third-party, the Company will pay former InteKrin’s stockholders cash based on a certain percentage of fees received pursuant to such compound transaction. That payment ranges from 60% of the fees received within one year to 10% after the third anniversary of the date of the final dose administered to the final patient in Phase 2 clinical trial.
	At the time of the acquisition, the Company estimated that the probability of achieving the compound transaction agreement event was 7.5% of the fair value of this contingent consideration based on a probability weighted determination of both the range of the amount and the likelihood of achieving the estimated payouts. At the acquisition date, the fair value of this contingent consideration from the compound transaction payment was determined to be $0.5 million.
	At the acquisition date, the Company valued the two contingent consideration scenarios using a probability-weighted discounted cash flow approach. A probability of reaching each contingent consideration threshold was estimated by management. A probability-weighted value was determined by multiplying the probability of achieving a contingent payment threshold by the respective contingent payment. The expected cash flows were discounted at a rate selected to capture the risk of achieving the contingent payment thresholds and earning the contingent payment. This risk is composed of InteKrin’s continued development, a specific risk factor associated with meeting the contingent consideration threshold and related payout and counterparty risk associated with the payment of the contingent consideration.
	As of December 31, 2014, the fair value of this contingent consideration liability increased to $6.5 million to reflect the updated fair value estimate of the liability and accordingly $5.2 million was recognized as an expense in the consolidated statement of operations during year ended December 31, 2014. The increase in the updated fair value of the contingent consideration is due to changes in the Company’s estimate of reaching each contingent consideration threshold and the increase in the fair value of the Company’s common stock (see Note 3).
	Goodwill
	Goodwill resulting from this acquisition comprises the excess of the purchase price over the fair value of the underlying net assets acquired and primarily represents the strategic relationship acquired with InteKrin’s investors. None of this goodwill will be deductible for tax purposes. Under the applicable accounting guidance, goodwill will not be amortized but will be tested for impairment on an annual basis or more frequently if certain indicators are present. As of December 31, 2014, there have been no such impairments.
	Government Contract with the Russian Government
	In 2012, InteKrin Russia, a subsidiary of InteKrin, was awarded a contract by the Ministry of Industry and Trade of the Russian Federation to perform scientific research and experimental development work for treatment of multiple sclerosis and conducting its preclinical and clinical studies for a total aggregate amount of 147.9 million RUB ($2.6 million in US dollars as of December 31, 2014) which was expanded multiple years from 2012 to 2015. The contract amount related to the 2014 research period was expected to be 40.0 million RUB. Subsequent to the Company’s acquisition of InteKrin in February 2014, the Company received 12.0 million RUB and 28.0 million RUB in the first and fourth quarter of 2014, respectively.  These advance receipts of funding were deferred until the Company met all the revenue recognition criteria, in the four quarter of 2014.  The Company recognized revenue of 40.0 million RUB ($732,000 based on the exchange rate on the date the revenue was recognized) as other revenue in the consolidated statements of operations. The remaining amounts available under the government contract for 2015 is 39.4 million RUB. None of these amounts have been received as of December 31, 2014.

Debt_Obligations

Debt Obligations	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt Obligations	7	Debt Obligations
	Convertible Notes Issued in 2011
	From July to December 2011, the Company entered into convertible note agreements (the “2011 Notes”) with investors, which included multiple closings. In July 2011, the initial closing had an aggregate principal amount of $3.8 million, and the subsequent closings occurred in August, October, November and December 2011 raising an aggregate principal amount of $6.6 million. The initial closing of $3.8 million consisted of $3.5 million of cash received from the investors and $260,000 of accrued employee compensation and/or bonuses payable by the Company that were converted into convertible notes for the balances owed to the individuals. The 2011 Notes bore interest of 8% per annum and had a maturity date of March 31, 2012. The outstanding principal and accrued interest on the 2011 Notes were convertible: (i) automatically upon a financing event in which the Company issued newly authorized shares of stock into that same stock at a conversion price equal to the price paid by the other investors in that financing event, (ii) upon a change of control or IPO, at the option of the note holder, into shares of Series A convertible preferred stock at a conversion price of $1.2503 per share or (iii) upon the maturity date, at the request of the majority note holders, if the financing event above had not occurred on or before the maturity date, into shares of Series A convertible preferred stock at a conversion price of $1.2503 per share. In connection with the issuance of the 2011 Notes, the Company issued warrants (the “2011 Warrants B”) to purchase shares of its preferred stock at an exercise price of $0.0167 per share (see Note 9).
	Upon issuance of the 2011 Notes, the Company recorded the fair value of the warrants of $2.7 million as a debt discount and convertible preferred stock warrant liability (see Note 9). The Company also recorded a beneficial conversion feature of $5.4 million as a debt discount with a corresponding increase to additional paid-in capital. The debt discount was accreted using the effective interest method as additional interest expense over the term of the 2011 Notes.
	In January 2012, as a result of the Series B convertible preferred stock financing event (see Note 11), the outstanding principal of $10.4 million and accrued interest of $236,000 related to the 2011 Notes automatically converted into 1,524,134 shares of Series B convertible preferred stock using a conversion price which represented the same issuance price of $6.9749 per share paid by other Series B investors. Contemporaneously, the Company reacquired the beneficial conversion feature and recorded $6.4 million related to the gain on the extinguishment of the 2011 Notes which is reflected in other income (expense), net in the consolidated statement of operations. In addition, the 2011 Warrants B became warrants to purchase 352,448 shares of Series B convertible preferred stock for $0.0167 per share.
	During the year ended December 31, 2012, the Company recognized interest expense of $1.5 million related to the accrued interest and amortization of debt discount, of which $1.0 million related to beneficial conversion feature, $433,000 related to debt discount amortization and $53,000 related to interest on the outstanding debt.
	Convertible Notes Issued in 2013
	During July 2013 to September 2013, the Company entered into convertible note agreements (the “Bridge Loans”) with various stockholders, employees and institutions for an aggregate principal amount of $10.0 million. The Bridge Loans accrued interest of 8% per annum and would mature on July 15, 2014. The principal and the accrued interest on the Bridge Loans were convertible: (i) automatically upon a qualified equity financing into shares of the series of capital stock issued in such financing at a conversion price equal to the price paid by other investors in the financing, (ii) at the option of the holder, upon a change of control of Coherus, into shares of Series B convertible preferred stock at a conversion price of $6.9749 per share, (iii) automatically upon an IPO into shares of Series B convertible preferred stock at a conversion price equal to the lesser of $6.9749 per share or the price per share paid in the IPO or (iv) upon the election of the holders, if none of the liquidity events stated above had occurred on or before maturity date, into shares of Series B convertible preferred stock at a conversion price of $6.9749 per share. In addition, upon a change of control, the holders were entitled to receive a cash payment equal to 400% of the outstanding principal, plus accrued interest, in lieu of conversion into Series B convertible preferred stock if the Company did not meet the QLT threshold. The QLT is deemed to have been achieved when (i) the Company has entered into a transaction with a third party to sell or offer to sell any product candidates of the Company that provides for aggregate cash payments of at least $50.0 million payable within 12 months and (ii) the Company has received cash payments of at least $25.0 million within 12 months following the execution of the agreement due to any milestones. On December 9, 2013, the QLT was deemed to have been achieved.
	In connection with the Bridge Loans, the Company also issued warrants to purchase shares of its convertible preferred stock at an exercise price of $0.0167 per share. The determination of the number of shares issuable pursuant to the 2013 warrants was determined based on 300% of the principal amount of the Bridge Loans divided by the conversion price. In addition, at the issuance date of the notes, there was a beneficial conversion feature. The total aggregate Bridge Loans of $10.0 million were less than the initial fair value of the warrants of $13.6 million at the issuance date. Therefore $10.0 million was recognized as debt discount, and the difference of $3.6 million was immediately charged to other income (expense), net in the consolidated statement of operations and comprehensive loss as the carrying value of the debt could not be reduced to less than zero. No value was recorded initially for the beneficial conversion feature since the carrying value of the debt was zero. The debt discount of $10.0 million was accreted using the effective interest method as an additional interest expense over the term of the Bridge Loans.
	The Bridge Loans redemption features were determined to be embedded derivatives requiring bifurcation and separate accounting. The fair value of the embedded derivative liability at issuance was determined to be $4.1 million. As a result of the fair value of the warrant debt discount reducing the debt to zero at the time of the issuance as discussed above, the estimated fair value of the derivative liability of $4.1 million was recognized within other income (expense), net, in the consolidated statement of operations and comprehensive loss and as a derivative liability on the consolidated balance sheet upon issuance. Changes in the fair value of the embedded derivative have also been recorded within other income (expense), net, in the consolidated statement of operations and comprehensive loss. The Company periodically remeasures the derivative liability to fair value.
	In December 2013, following the receipt of the upfront license payment from Baxter license agreement (see Note 5), the Company met the qualified licensing threshold (“QLT”). As a result, upon a change of control, the redemption feature related to the holders’ option to receive a cash payment in lieu of conversion into Series B convertible preferred stock was reduced from 400% to 100% of the outstanding principal, plus accrued interest and the associated embedded derivative liability was reduced to zero.
	During the year ended December 31, 2013, the Company recognized total interest expense of $4.8 million related to the accrued interest and amortization of the debt discount.
	The Bridge Loans were collateralized by a security interest in all assets, tangible and intangible, of the Company, subject to a prior security interest of Cook on the Company’s property and equipment in Camarillo, California. Upon the issuance of Series C convertible preferred stock in May 2014, all security interests to the Company’s asserts, tangible and intangible, were released.
	In May 2014, the Company completed an equity financing of Series C convertible preferred stock and, as a result, the Bridge Loans and related accrued interest of $10.6 million automatically converted into 1,058,089 shares of Series C convertible preferred stock based on the price per share paid by other investors in the financing. In connection with the extinguishment of the Bridge Loans, the Company reacquired the beneficial conversion feature. The intrinsic value of the beneficial conversion feature at the date of the Bridge Loans extinguishment was $3.9 million. This amount is reflected in additional paid in capital. The Company recorded a gain from the extinguishment of the debt in the amount of $2.0 million which is reflected in other income (expense), net in the consolidated statement of operations.
	In addition, as the warrants could be exercised for Series B convertible preferred stock any time after achieving a QLT, which was met on December 9, 2013 and before the Series C convertible preferred stock financing, in April and May 2014, all holders of these warrants elected to fully exercise warrants for 4,279,620 shares of Series B convertible preferred stock.
	During the year ended December 31, 2014, the Company recognized total interest expense of $3.9 million related to the accrued interest and amortization of the debt discount.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8	Commitments and Contingencies
	Purchase Commitments
	The Company enters into contracts in the normal course of business with contract research organizations for preclinical studies and clinical trials and contract manufacturing organizations (“CMOs”) for the manufacture of clinical trial materials. As of December 31, 2014, the Company has a commitment of $4.8 million with CMOs for the manufacture of clinical trial material due within a year. The Company has an agreement with Medpace, Inc. (“Medpace”), a CRO, which provides for a minimum fee commitment of $35.0 million, in aggregate, for clinical trial services; however, the agreement is cancelable without cause by either party upon 30 days prior notification by either party. As of December 31, 2014, $20.7 million of the services related to this agreement had been performed or paid for.
	Facility Leases
	The Company leases office spaces for its corporate headquarters in Redwood City, California and for laboratory facilities in Camarillo, California under operating lease agreements. Rent expense is recognized on a straight-line basis over the term of the lease and accordingly, the Company records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. The corporate headquarters lease expires in April 2017, and the laboratory lease expires in June 2017 with an option to extend for three years.
	The future minimum lease payments for these facilities as of December 31, 2014 are as follows (in thousands):
	Year ending December 31,
	2015		$	1,082
	2016			1,117
	2017			404
	Total minimum lease payments		$	2,603
	Rent expense was $763,000, $428,000 and $371,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	Guarantees and Indemnifications
	In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future, but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company would assess the likelihood of any adverse judgments or related claims, as well as ranges of probable losses. In the cases where the Company believes that a reasonably possible or probable loss exists, it will disclose the facts and circumstances of the claims, including an estimate range, if possible. As of December 31, 2014, the Company does not have any material indemnification claims that were probable or reasonably possible and consequently has not recorded related liabilities.

Convertible_Preferred_Stock_Wa

Convertible Preferred Stock Warrants	12 Months Ended
	Dec. 31, 2014
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock Warrants	9	Convertible Preferred Stock Warrants
	The following table sets forth a summary of the convertible preferred stock warrants and the related estimated fair values as of December 31, 2013 (in thousands, except share data). No convertible preferred stock warrants were outstanding as of December 31, 2014:
			31-Dec-13
			Shares Underlying			Estimated Fair
			the Warrants			Value
	Warrants to purchase Series A convertible			63,923		$	170
	preferred stock — 2011 Warrants A
	Warrants to purchase Series B convertible			295,101			1,122
	preferred stock — 2011 Warrants B
	2013 Warrants			4,279,620			22,959
	Total			4,638,644		$	24,251
	2011 Warrants A
	In January 2011, in conjunction with the issuance of the 2011 Notes, the Company issued warrants to purchase shares of its newly authorized shares of preferred stock upon a financing event (“2011 Warrants A”). In March 2011, as a result of the Series A convertible preferred stock financing event, the January 2011 convertible promissory notes and related accrued interest automatically converted into Series A convertible preferred stock and the 2011 Warrants A became exercisable warrants to purchase 63,923 shares of Series A convertible preferred stock with an exercise price of $1.2503 per share. The warrants would expire at the earlier of: (i) January 25, 2016, (ii) upon the closing of the Company’s IPO, or (iii) upon the closing of the Company’s change of control. The Company initially valued the 2011 Warrants A at $53,000 using the Option Pricing Model (“OPM”) that allocated total equity value to all the Company’s equity securities in the capital structure at the time of issuance including potentially dilutive equity securities. These analyses generally used a backsolve approach that implies the total equity and common stock value from a round of preferred financing. Immediately prior to the closing of the Company’s IPO in November 2014, all of the outstanding warrants were exercised, for cash or on a net cash basis for 62,251 shares of Series A convertible preferred stock resulting in cash proceeds of $55,000.
	2011 Warrants B
	From July to December 2011, the Company issued the 2011 Warrants B with an exercise price of $0.0167 per share in conjunction with the issuance of the 2011 Notes (see Note 7). The warrants would expire at the earlier of: (i) seven years from the issuance dates, or (ii) upon the closing of the Company’s change of control or IPO. If the warrant holders had not exercised the warrants prior to the closing of the change of control or IPO, the warrants would have automatically been deemed to be net exercised in full immediately prior to the closing of the change of control or IPO. The 2011 Warrants B were exercisable upon the earlier of: (i) a financing event in which the Company issued newly authorized shares of stock, into that same stock at a conversion rate equal to the quotient obtained by dividing the sum of (a) 30% of the principal loan amount of the initial closing and (b) 20% of the principal loan amount of subsequent closing by the price paid by other investors in the financing event, or (ii) upon a change of control, an IPO, or maturity date, into Series A convertible preferred stock at the conversion rate equal to the quotient obtained by dividing the sum of (a) 30% of the principal loan amount of initial closing and (b) 20% of the principal loan amount of subsequent closing by $1.2503 per share.
	The estimated fair value of the warrants at issuance was $2.7 million based on probability-weighted present values of the warrants under the qualifying event scenarios with the follows assumptions:
	Issuance Date		Next Financing Event in		Change of Control, IPO or
			Which the Company		Maturity Date
			Issued Newly Authorized
			Shares of Preferred Stock
	21-Jul-11		35%		65%
	31-Aug-11		50%		50%
	31-Oct-11		75%		25%
	29-Nov-11		85%		15%
	21-Dec-11		90%		10%
	In January 2012, as a result of the Series B convertible preferred stock financing event, the 2011 Warrants B became exercisable warrants to purchase 352,448 shares of Series B convertible preferred stock. In June 2012, warrants to purchase 57,347 of Series B preferred stock were exercised, resulting in cash proceeds of approximately $1,000 and a reclassification of fair value of convertible preferred stock warrants to Series B preferred stock of $400,000. During April and May 2014, warrants to purchase 172,042 shares of Series B convertible preferred stock were cash exercised for $3,000 and the remaining outstanding warrants were exercised, for cash or on a net basis resulting in the issuance of 123,051 shares of Series B convertible preferred stock for $2,000 immediately prior to the closing of the Company’s IPO in November 2014.
	2013 Warrants
	From July to September 2013, the Company issued the 2013 Warrants with the exercise price of $0.0167 per share in conjunction with the issuance of the Bridge Loans (see Note 7). The warrants would expire at the earlier of: (i) seven years from issuance dates, or (ii) upon the closing of the Company’s change of control or IPO. If the warrant holders had not exercised the warrants prior to the closing of the change of control or IPO, the warrants would have automatically be deemed to be net exercised in full immediately prior to the closing of the change of control or IPO.
	The determination of the number of shares pursuant to the 2013 Warrants was equal to 300% of the principal amount of the Bridge Loans divided by the conversion price, as defined. The 2013 Warrants were exercisable upon the earlier of: (i) a financing event in which the Company issued newly authorized shares of stock, into that same stock at a conversion price equal to the price paid by other investors in the financing event, (ii) an occurrence of a QLT, as defined under the Bridge Loans, into shares of Series B convertible preferred stock at a conversion price equal to $6.9749 per share, (iii) election by the warrant holder to convert the underlying note upon a change of control, into shares of Series B convertible preferred stock at a conversion price equal $6.9749 per share, (iv) an occurrence of an IPO, into shares of the Company’s common stock at a conversion price equal to the lesser of (a) $6.9749 per share, or (b) the price per share paid in the IPO, or (v) the maturity date if the financing event stated in (i) above has not occurred, into shares of Series B convertible preferred stock equal to the conversion price of $6.9749 per share.
	The estimated fair value of the 2013 Warrants at issuance was $13.6 million based on probability-weighted values of the warrants under the qualifying event scenarios. For scenarios (i) and (ii), the cash flow method was used to value the present values of the warrants based on the warrant coverage, as adjusted for risk-adjusted discount rate of 30%. For scenarios (iii), (iv) and (v), the present values of the warrants were based on the fair value per share of the Series B convertible preferred stock using the PWERM. The Company weighed the scenarios based on management’s estimate of the timing and probability of each qualifying event as of each of the issuance dates and then again at the end of each quarter for the mark to market adjustments. The Company recognized the fair value of the 2013 Warrants up to the total aggregate Bridge Loans of $10.0 million as the debt cannot be reduced to less than zero. The remaining $3.6 million of the total fair value of the 2013 Warrants was recognized immediately within other income (expense), net, in the consolidated statement of operations. In December 2013, following the receipt of the upfront license payment from the Baxter license agreement (see Note 5), the Company met the QLT criteria. As a result, the 2013 Warrants became exercisable to purchase 4,279,620 shares of Series B convertible preferred stock. During April and May 2014, warrants to purchase 4,279,620 shares of Series B convertible preferred stock were exercised for $71,000.
	The 2011 Warrants A, 2011 Warrants B and 2013 Warrants are classified as convertible preferred stock warrant liabilities and are subject to remeasurement at each balance sheet date. The changes to the fair value of the warrants were recognized as a component of other income (expense), net, in the consolidated statements of operations. The net change in the fair value of the warrant liability was an increase of $15.9 million, an increase of $8.9 million and a decrease of $0.6 million for the years ended December 31, 2014, 2013 and 2012, respectively. The Company adjusted the liability for changes in fair value at the time of the exercise and then reclassified the liability to the respective series of preferred stock. As the result of all of the outstanding warrant exercises during 2014, the Company reclassified $1.0 million and $39.3 million to Series A and Series B preferred stock. Any remaining warrants outstanding immediately prior to the Company’s IPO in November 2014 were exercised, for cash or on a net basis.

Common_Stock_Warrants

Common Stock Warrants	12 Months Ended
	Dec. 31, 2014
Warrants And Rights Note Disclosure [Abstract]
Common Stock Warrants	10	Common Stock Warrants
	In March 2014, the Company issued warrants to purchase 553,274 shares of common stock with the exercise price of $1.667 per share to two employees and one consultant for past services. The warrants were vested and exercisable upon issuance and would have expired at the earlier of: (i) March 28, 2024, (ii) an IPO or (iii) the consummation of a liquidation event. If the holders had not exercised these warrants prior to the closing of a liquidation event or an IPO, these warrants would have automatically been net exercised. The Company valued the warrants at $2.7 million using the Black-Scholes option-pricing model with the following assumptions on the date of grant: exercise price of $1.667 per share, fair value of the common stock of $5.73 per share, expected volatility of 93% and 96% for the employee and consultant warrants, respectively, risk-free interest rate of 1.74% and 2.73% for the employee and consultant warrants, respectively, expected terms of 5 and 10 years for the employee and consultant warrants, respectively, and dividend yield of zero. The grant date fair value per warrant share was $4.95 for employees and $5.42 for the consultant, resulting in warrant valuations of $2.6 million and $144,000 for the employees and consultant, respectively. Due to the immediate vesting and exercisability of the warrants upon issuance, the Company immediately recognized $1.3 million and $1.4 million of stock-based compensation in research and development expense and general and administrative expense, respectively, in the consolidated statement of operations.  In November 2014, all of the warrants outstanding to purchase common stock were net exercised, which resulted in the issuance of 491,580 shares of common stock upon the closing of the IPO.

Convertible_Preferred_Stock_an

Convertible Preferred Stock and Stockholders Equity (Deficit)	12 Months Ended
	Dec. 31, 2014
Equity Method Investment Summarized Financial Information Liabilities And Equity [Abstract]
Convertible Preferred Stock and Stockholdersb Equity (Deficit)	11	Convertible Preferred Stock and Stockholders’ Equity (Deficit)
	Common Stock
	In October 2014, the Company’s board of directors and stockholders approved the amendment and restatement of the Company’s certificate of incorporation to be effective immediately prior to the consummation of the IPO. The Amended and Restated Certificate of Incorporation was filed on November 12, 2014, which provides for 300,000,000 authorized shares of common stock with a par value of $0.0001 per share and 5,000,000 authorized shares of preferred stock with a par value of $0.0001 per share.
	Convertible Preferred Stock
	In January 2012, the Company issued 3,225,854 shares of Series B convertible preferred stock in an initial closing at a price of $6.9749 per share for net cash proceeds of $20.3 million. An additional 1,524,134 shares of Series B convertible preferred stock were issued at the same price per share in exchange for the conversion of $10.6 million of the 2011 Notes B and related accrued interest (see Note 7). In June 2012, upon the exercise of 57,347 shares of Series B convertible preferred stock warrants, the $400,000 of the fair value of the convertible preferred stock warrant liability was reclassified to the carrying value of the Series B convertible preferred stock. In December 2012, the Company issued 1,146,970 shares of Series B convertible preferred stock in a subsequent closing at a price of $6.9749 per share for net cash proceeds of $6.6 million.
	Contemporaneously with the initial and subsequent closings of the Series B convertible preferred stock, the Company issued 501,799 and 1,725,472 shares of Series B convertible preferred stock in January 2012 and December 2012, respectively, to various vendors in exchange for past and future services. The shares issued in January 2012 and December 2012 was based on the $6.9749 price per share which was the same price paid by the investors in the initial and subsequent closings for total value of $3.5 million and $12.0 million, respectively. To the extent the vendors had future services to be provided, the Company initially recorded a prepayment for the future services and a corresponding amount to Series B convertible preferred stock, as the shares were not subject to vesting or repurchase. The prepayments were amortized to research and development expense based on the invoiced amounts for such services as the services were performed.
	Of the 1,725,472 shares of Series B convertible preferred stock issued in exchange for past and future services, pursuant to the terms of the agreement with Cook, 716,856 shares of Series B convertible preferred stock valued at $5.0 million held by Cook were contingently subject to repurchase by the Company for cash based upon the occurrence of certain events, none of which occurred or were probable as of December 31, 2013. In February 2014, these shares were purchased by another party resulting in the termination of the Company’s repurchase obligation.
	In May 2014, the Company completed a financing resulting in the issuance of 5,488,892 shares of Series C convertible preferred stock, for net cash proceeds of $54.7 million. In conjunction with the Series C convertible preferred stock financing, the Bridge Loans and the related accrued interest were automatically converted into 1,058,089 shares of Series C convertible preferred stock at the price per share of such financing, and the collateralized security interest of the Company’s assets, tangible and intangible, under the Bridge Loans was released. In addition, the Company issued 9,997 shares of Series C convertible preferred stock in exchange for consulting services.
	The Company recorded the convertible preferred stock at fair value on the dates of issuance. The Company classified the convertible preferred stock outside of stockholders’ deficit because the shares contained liquidation features that were not solely within the Company’s control.
	During April and May 2014, warrants to purchase 4,451,662 shares of Series B convertible preferred stock were exercised into Series B convertible preferred stock for $74,000, which included the 4,279,620 shares of Series B convertible preferred stock warrants related to the Bridge Loan (see Note 9). ). In November 2014, in connection with the closing of the IPO, warrants to purchase 62,251 shares and 123,051 shares of Series A and B convertible preferred stock, respectively, were exercised on a cash or net basis for $57,000.
	In connection with the closing of the IPO in November 2014, all outstanding shares of Series A, Series B and Series C convertible preferred stock shares were converted into 21,316,519 shares of common stock on a one-for-one basis. As such, no convertible preferred stock shares were outstanding as of December 31, 2014.
	As of December 31, 2013, the outstanding convertible preferred stock was as follows (in thousands, except share data):
	31-Dec-13		Shares Authorized		Shares Issued		Carrying Value		Liquidation
					and Outstanding				Preference
	Series A			1,800,000		972,330	$	1,191	$	1,216
	Series B			26,290,997		8,181,576		53,504		57,066
				28,090,997		9,153,906	$	54,695	$	58,282
	The rights, preferences and privileges of the convertible preferred stock were as follows:
	Conversion
	Each share of Series A, B and C convertible preferred stock, was convertible into common stock at the option of the holder, at an initial conversion ratio of 1:1. This initial conversion ratio was subject to certain adjustments, from time to time, for dilution. Conversion of preferred stock into common stock was automatic at its then effective conversion rate immediately upon the occurrence of certain events.  Upon the completion of the IPO, all shares of convertible preferred stock were converted into 21,316,519 shares of common stock.
	Voting
	The holders of the Series A, B and C convertible preferred stock were entitled to voting rights equal to the number of shares of common stock into which each share of convertible preferred stock could be converted into at the record date for a vote or consent of stockholders, except as otherwise required by law, and had voting rights and powers equal to the voting rights and powers of the common stockholders.
	Dividends
	The holders of the Series A, B and C convertible preferred stock were entitled to receive dividends payable out of any funds or assets legally available, prior and in preference to any declaration or payment of any dividend on the common stock of the Company. No dividends were ever declared.
	Liquidation
	In the event of any liquidation, dissolution or winding up of the Company, either voluntary or involuntary, the holders of Series A, B and C convertible preferred stock were entitled to receive, prior and in preference to any distribution of any of the assets or surplus funds of the Company to the holders of common stock, amounts per share equal to the original issue price (as adjusted for any stock dividends, combinations or splits), plus any declared but unpaid dividends on such shares. If upon the occurrence of such event, the assets and funds distributed among the holders of the convertible preferred stock were insufficient to permit the payment to such holders of the full aforesaid preferential amounts, then, the entire assets and funds of the Company legally available for distribution were to be distributed with equal priority and pro rata among the holders of the convertible preferred stock.

Stock_Option_Plans_and_StockBa

Stock Option Plans and Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Plans and Stock-Based Compensation	12	Stock Option Plans and Stock-Based Compensation
	Restricted Common Stock (“Founders Shares”)
	In October 2010 and January 2011, the Company issued 4,130,173 shares and 968,804 shares of common stock, respectively, with a purchase price of $0.0083 per share to its founders under the Founder Shares agreements. Under the Founders Shares agreements, the Company has the right to repurchase the common stock which right lapses monthly in equal installments over four years. In order to vest, the holders are required to provide continued service to the Company. Upon vesting, the appropriate amounts are transferred from liabilities to additional paid in capital. If the holder of any unvested restricted common stock is terminated for any reason, the Company has the right to repurchase the unvested shares at the stockholder’s original purchase price. As such, the shares subject to future vesting were not deemed outstanding for accounting purposes until the shares vested. In July 2012 and March 2014, the Company repurchased 286,817 and 239,952 shares of founders’ common stock from founders at $0.0083 per share, respectively.
	A summary of the Company’s non-vested restricted stock for the periods is as follows:
			Number of
			Shares
	Non-vested as of December 31, 2011			3,644,858
	Vested			(1,207,062	)
	Repurchased by the Company			(286,817	)
	Non-vested as of December 31, 2012			2,150,979
	Vested			(1,387,650	)
	Non-vested as of December 31, 2013			763,329
	Vested			(742,084	)
	Non-vested as of December 31, 2014			21,245
	As of December 31, 2014 and 2013, the Company had 21,245 and 763,329 unvested shares of common stock which were subject to repurchase by the Company. As such, approximately $200 and $5,000 were recorded as accrued and other liabilities, in the accompanying consolidated balance sheets as of December 31, 2014 and 2013, respectively. The unvested shares of common stock will continue to vest with the founders’ continued service to the Company pursuant to the Founders Shares agreements.
	The Company recognized stock-based compensation over the vesting term of four years based on the fair value of the common stock on the dates of issuance. The restricted common stock granted to an employee is valued using the Black-Scholes options pricing model based on the common stock fair value at the time of the grant. For restricted common stock issued to consultants, the Company remeasures the fair value of the restricted shares as they vest at each reporting period using the Black-Scholes option-pricing model reflecting the remaining vesting period.
	The stock-based compensation expense recorded related to the founder’s shares was as follows (in thousands):
			Year Ended December 31,
			2014			2013			2012
	Research and development		$	1,547		$	227		$	232
	General and administrative			4			1,054			110
			$	1,551		$	1,281		$	342
	The estimated weighted-average grant date fair value of restricted stock issued in 2011 and 2010 for both years was $0.41 per share. No restricted common stock was granted in 2014 or 2013. The total unrecognized stock compensation expense as of December 31, 2014, of $9,000 will be amortized as the shares vest over the remaining service period of 0.3 years.
	2010 Stock Plan
	In 2010, the Company adopted the 2010 Stock Plan (the “2010 Plan”) and granted options under this plan until November 2014 which is when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding under the 2010 Plan. The 2010 Plan provided for the Company to grant shares and/or options to purchase shares of common stock to employees, directors, consultants, and other service providers at prices not less than the fair market value at the date of grant for incentive stock options and nonstatutory options. These options were granted to generally vest over four years, expire ten years from the date of grant, and are generally exercisable after vesting. Unvested options exercised are subject to the Company’s repurchase right that lapses as the options vest. As of December 31, 2014 and 2013, no shares were subject to repurchase under the 2010 Plan.
	In November 2014, the board of directors adopted the Company’s 2014 Equity Incentive Award Plan (the “2014 Plan”) and any remaining unissued shares available under the 2010 Plan were transferred into the 2014 Plan. As such, no more options may be issued under the 2010 Plan.
	As of December 31, 2014, a total of 5,560,345 shares of common stock are subject to options outstanding under the 2010 plan, which shares will become available under the 2014 Plan to the extent the options are forfeited or lapse unexercised.
	2014 Equity Incentive Award Plan
	In October 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Equity Incentive Plan (the “2014 Plan”), effective upon the date upon which the registration statement for the IPO was declared effective, which was November 6, 2014. As of the date of the IPO, the Company reserved for issuance under the 2014 Plan a total of 2,300,000 shares of its common stock, plus any additional shares that would otherwise return to the 2010 Plan as a result of forfeiture, termination or expiration of awards previously granted under the 2010 Plan. In addition, the 2014 Plan provides for annual increases in the number of shares available for issuance thereunder on the first business day of each fiscal year, beginning with 2015, equal to four percent (4%) of the number of shares of the Company’s common stock outstanding as of such date or a lesser number of shares as determined by the Company’s board of directors.
	Employee Stock Purchase Plan
	In October 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Employee Stock Purchase Plan (“ESPP”). The Company will reserve for issuance 320,000 shares of its common stock and provide for annual increases in the number of shares available for issuance on the first business day of each fiscal year, beginning with the Company’s fiscal year following the year of this offering, equal to the lesser of one percent (1%) of the number of shares of the Company’s common stock outstanding as of such date, 320,000 shares of common stock, or a number of shares as determined by the Company’s board of directors.
	The following table sets forth the summary of option activities under the 2014 and 2010 Plans:
						Options Outstanding
			Shares Available			Number of			Weighted-Average
			for Grant			Options			Exercise Price
	Balances at December 31, 2011			14,999			974,797		$	0.358
	Authorized			1,520,830			—			—
	Granted - at fair value			(611,285	)		611,285			2.084
	Exercised			—			(22,307	)		0.008
	Forfeited			28,680			(28,680	)		0.008
	Balances at December 31, 2012			953,224			1,535,095		$	1.057
	Authorized			1,586,570			—			—
	Granted - at fair value			(853,244	)		853,244			2.084
	Granted - below fair value			(786,018	)		786,018			1.417
	Exercised			—			(3,248	)		2.084
	Forfeited			123,713			(123,713	)		1.271
	Balances at December 31, 2013			1,024,245			3,047,396		$	1.427
	Authorized			4,399,580			—			—
	Granted - at fair value			(614,062	)		614,062			13.907
	Granted - below fair value			(2,703,441	)		2,703,441			1.833
	Exercised			—			(48,414	)		1.144
	Forfeited			546,178			(546,178	)		1.831
	Balances at December 31, 2014			2,652,500			5,770,307		$	2.909
	Additional information related to the status of options as of December 31, 2014 is summarized as follows:
			Number of Options			Weighted-Average			Weighted-Average			Aggregate Intrinsic
						Exercise Price			Contractual Terms			Value (in thousands)
									(Years)
	Options outstanding			5,770,307		$	2.909			8.65		$	77,383
	Options vested and expected to vest			5,764,337		$	2.909			8.64		$	77,303
	Options vested			2,364,401		$	1.483			8.49		$	35,080
	Options exercisable			2,365,651		$	1.482			7.9		$	35,101
	Valuation of Awards Granted to Employees
	The Company estimated the fair value of each stock award on the date of grant using the Black-Scholes option-pricing model. The weighted average assumptions used to value options granted to employees under the Plan during the years ended December 31, 2014, 2013 and 2012 were as follows:
			Year Ended December 31,
		2014			2013			2012
Expected term (years)			6.5			5.51			6.04
Expected volatility			99	%		108	%		110	%
Risk-free interest rate			2.05	%		1.23	%		0.93	%
Expected dividend yield			0	%		0	%		0	%
Expected Term
The expected term represents the period for which the stock-based awards are expected to be outstanding and is based on the options’ vesting term, contractual term and industry peers. The Company did not have sufficient historical information to develop reasonable expectations about future exercise patterns and post vesting employment termination behavior.
Expected Volatility
The Company used an average historical stock price volatility of industry peers as representative of future stock price volatility since the Company does not have any trading history for its common stock.
Risk-Free Interest Rate
The Company based the risk-free interest rate by using an equivalent to the expected term based on the U.S. Treasury constant maturity rate as of the date of grant.
Expected Dividends
The Company has not paid and does not anticipate paying any dividends in the near future, and therefore used an expected dividend yield of zero in the valuation model.
The stock-based compensation expense recorded related to options granted to employees was as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
Research and development		$	1,580		$	431		$	30
General and administrative			3,934			309			65
		$	5,514		$	740		$	95
During the years ended December 31, 2014, 2013 and 2012, the total estimated fair value of the options vested was $4.2 million, $0.7 million and $95,000, respectively and the estimated weighted-average grant-date fair value of options granted was $6.65, $1.88 and $1.73 per share, respectively. The aggregate intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $391,000, $0 and $46,000, respectively.
As of December 31, 2014, total unrecognized stock-based compensation expenses related to unvested employee stock options was $18.5 million, which is expected to be recognized on a straight-line basis over a weighted-average period of approximately 3.28 years.
In November 2014, the Company entered into a separation agreement with its former CFO and granted accelerated vesting of options and extended the exercise period for those vested options. In connection with the option modification, the Company recognized stock-based compensation expense of $1.2 million to general and administrative expense in its consolidated statements of operations for the year ended December 31, 2014, which is included in the $3.9 million in the above stock-based compensation table.
Nonemployees Stock-Based Compensation
The Company granted 113,913 and 74,983 stock options to purchase shares of common stock to nonemployees during the years ended December 31, 2014 and 2013. The weighted-average exercise price of the options granted in 2014 and 2013 was $4.42 and $1.42 per share, respectively. The Company did not grant any stock options to purchase shares of common stock to nonemployees during the year ended December 31, 2012. For the years ended December 31, 2014, 2013 and 2012, the Company recorded stock-based compensation expense related to options granted to nonemployees of $1.3 million, $24,000 and $6,000, respectively. The Company remeasures the fair value of the unvested nonemployee options at each period using the Black-Scholes option-pricing model reflecting the same assumptions as applied to employee options in each of the reported years, other than the expected life, which is assumed to be the remaining contractual life of the options.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	13	Income Taxes
	The Company utilizes the liability method of accounting for deferred income taxes. Under this method, deferred tax liabilities and assets are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities. A valuation allowance is established against deferred tax assets because, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense.
	A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:
			Year Ended December 31,
			2014			2013			2012
	Percent of pre-tax income:
	U.S. federal statutory income tax rate			34	%		34	%		34	%
	State taxes, net of federal benefit			(1.65	)		3.97			6.68
	Permanent items			(10.80	)		(12.40	)		5.65
	Research and development credit			3.11			4.53			—
	Net operating loss			0.01			—			—
	InteKrin purchase price allocation			0.73			—			—
	Other			0.02			—			(0.17	)
	Change in valuation allowance			(25.42	)		(30.10	)		(46.16	)
	Effective income tax rate			—	%		—	%		—	%
	Significant components of the Company’s net deferred tax assets as of December 31, 2014 and 2013 consist of the following (in thousands):
			December 31,
			2014			2013
	Net operating loss carryforwards		$	34,463		$	27,524
	Research and development credits			6,032			2,823
	Depreciation and amortization			854			26
	Stock-based compensation			1,428			82
	Other accruals			940			626
	Deferred revenue			12,762			2,413
	Gross deferred tax assets			56,479			33,494
	In-process research and development			(892	)		-
	Gross deferred tax liabilities			(892	)		-
	Total net deferred tax asset			55,587			33,494
	Less valuation allowance			(55,587	)		(33,494	)
	Net deferred tax assets		$	—		$	—
	The valuation allowance increased $22.1 million, $16.1 million and $15.1 million during the years ended December 31, 2014, 2013 and 2012, respectively.
	As of December 31, 2014, the Company had federal net operating loss carryforwards of approximately $97.3 million, which will start to expire beginning in 2031, and various state net operating loss carryforwards of approximately $64.5 million, which have various expiration dates beginning in 2031. Utilization of the net operating loss carryforwards and credits may be subject to a substantial annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization.
	As of December 31, 2014, the Company had federal research and development credit carryforwards of approximately $6.5 million, which will start to expire in 2031, and state research and development credit carryforwards of approximately $1.6 million, which can be carried forward indefinitely.
	In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. Due to the Company’s history of losses, and lack of other positive evidence, the Company has determined that it is more likely than not that its deferred tax assets will not be realized, and therefore, the deferred tax assets are fully offset by a valuation allowance at December 31, 2014 and 2013.
	At December 31, 2014, the portion of the federal net operating loss carryforwards related to stock option deductions is approximately $4.7 million, which is not included in the Company's gross or net deferred tax assets. Pursuant to ASC 718-740-25-10, the tax effect of the stock option benefit of approximately $1.6 million will be recorded to equity when they reduce cash taxes payable in the future.
	The Company files U.S, California, and other state income tax returns with varying statutes of limitations. The tax years from inception in 2010 forward remain open to examination due to the carryover of unused net operating losses and tax credits.
	A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2014 and 2013 is as follows (in thousands):
			Year Ended December 31,
			2014			2013			2012
	Balance at beginning of year		$	749		$	73		$	14
	Additions based on tax positions related to current year			861			319			59
	Additions for tax positions of prior years			2,206			357			—
	Balance at end of year		$	3,816		$	749		$	73
	The entire amount of the unrecognized tax benefits would not impact the Company’s effective tax rate if recognized. During the years ended December 31, 2014, 2013 and 2012, the Company did not recognize accrued interest and penalties related to unrecognized tax benefits. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease during the next 12 months.

Net_Loss_Per_Share_Attributabl

Net Loss Per Share Attributable to Coherus	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Coherus	14	Net Loss Per Share Attributable to Coherus
	The following table sets forth the computation of the basic and diluted net loss per share attributable to Coherus (in thousands, except share and per share data):
			Years Ended December 31,
			2014			2013			2012
	Numerator:
	Net loss attributable to Coherus		$	(87,133	)	$	(53,635	)	$	(33,018	)
	Denominator:
	Weighted-average common shares outstanding			8,520,100			4,828,214			4,963,883
	Less: weighted-average unvested common shares subject to			(333,571	)		(1,496,194	)		(2,881,261	)
	repurchase
	Weighted-average number of shares used in computing net loss per			8,186,529			3,332,020			2,082,622
	share attributable to Coherus, basic and diluted
	Net loss per share attributable to Coherus, basic and diluted		$	(10.64	)	$	(16.10	)	$	(15.85	)
	-1	Shares were excluded as such shares represent restricted common stock (founders’ shares) which is vesting contingently upon the holders’ continued services to the Company.
	The following outstanding dilutive potential shares have been excluded from the calculation of diluted net loss per share attributable to Coherus due to their anti-dilutive effect:
			December 31,
			2014			2013			2012
	Stock options outstanding			5,770,307			3,047,396			1,535,095
	Convertible preferred stock			—			9,153,906			9,153,906
	Convertible preferred stock warrants			—			4,638,644			359,024
	Total			5,770,307			16,839,946			11,048,025
	In addition, 358,384 shares of common stock contingently issuable upon the successful achievement of an objective associated with contingent consideration payable to former InteKrin stockholders have also been excluded from the calculation of diluted net loss per share attributable to Coherus.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	15	Related Party Transactions
	Notes Receivable from Founders
	In December 2011, the Company entered into unsecured promissory notes (“Notes Receivable”) agreement with the four founders of the Company. Of the four founders, three are members of the executive team of the Company. The aggregate amount of Notes Receivable was $133,000 at the issuance date and the Notes Receivable bore interest at 0.2% per annum. The Company recorded an imputed interest of 4% in relation to these notes. The principal amount of the Notes Receivable, together with all accrued and unpaid interest, was due and payable upon the earlier of: (i) December 26, 2014, (ii) immediately prior to the first filing of a registration statement in connection with an IPO, (iii) immediately prior to the Notes Receivable becoming prohibited under the rules and regulation of the Securities and Exchange Commission, (iv) immediately prior to an acquisition of the Company, (v) the termination of the borrower’s employment with the Company or (vi) the occurrence of an event of default.
	As of December 31, 2013, the Company had $107,000 of Notes Receivable outstanding, which is reflected as notes receivable from related parties in the Company’s consolidated balance sheets.
	In May 2014, the Company forgave the outstanding balance of Notes Receivable of $111,000 and the related accrued interest of approximately $1,000, which is reflected in the Company’s consolidated statement of operations for the year ended December 31, 2014, as interest expense.
	Daiichi Sankyo
	The Company entered into a license agreement with Daiichi Sankyo (see Note 5), under which the Company issued 2,867,426 shares of Series B convertible preferred stock. As such, Daiichi Sankyo was deemed to be a related party by ownership of more than 10% of the Company’s equity.  As of December 31, 2013, $6.1 million of revenue was deferred under this agreement, of which $2.0 million was included in current liabilities and $4.1 million was included in non-current liabilities in the consolidated balance sheet. Upon the consummation of the Company’s IPO, Daiichi Sankyo’s ownership percentage decreased to less than 10% of the Company’s equity; therefore, as of November 2014, Daiichi Sankyo was no longer considered a related party. As a result, the consolidated balance sheet as of December 31, 2014 no longer reflects these balances as related party amounts.  For the years ended December 31, 2014, 2013 and 2012, the Company recognized related party transactions of $1.9 million, $2.0 million and $1.9 million as collaboration and license revenue–related party in the Company’s consolidated statements of operations, respectively. In addition, the Company recognized $7.1 million, $1.3 million and $158,000  as a reduction of research and development expense related to the costs reimbursed by Daiichi Sankyo in the Company’s consolidated statements of operations for the years ended December 31, 2014, 2013 and 2012, respectively.
	Transactions Associated with Cook
	In January and December 2012, the Company issued a total of 2,150,569 shares of Series B convertible preferred stock to Cook as consideration for past and future services. As such, Cook was deemed to be a related party by ownership of more than 10% of the Company’s equity. These shares of Series B convertible preferred stock issued to Cook were valued based upon the price paid by investors in transactions which closed near the date of issuance. As of December 31, 2013, the Company had $3.0 million in prepaid assets (prepaid clinical, material, manufacturing and other–related parties) and $278,000 in receivables from related parties, reflected on the Company’s consolidated balance sheet associated with Cook. During the second quarter of 2014, Cook divested a majority of its shares of the Company’s Series B convertible preferred stock; therefore, as of December 31, 2014, Cook was no longer considered a related party. As a result, the consolidated balance sheet as of December 31, 2014 no longer reflects these balances as related party amounts. For the years ended December 31, 2014, 2013 and 2012, the Company recognized $4.5 million, $6.1 million and $15.8 million, respectively, of services rendered by Cook within research and development in the consolidated statements of operations.
	Transactions Associated with Medpace Agreement
	One member of the Company’s board of directors is also the chief executive officer of Medpace. As such, Medpace was deemed to be a related party. As of December 31, 2014, the Company had $6.0 million in prepaid assets (prepaid clinical, material, manufacturing and other–related parties), $1.9 million in accounts payable–related parties, and $3.0 million in accrued and other liabilities (accrued clinical, manufacturing and other–related parties), all reflected on the Company’s consolidated balance sheet associated with Medpace. As of December 31, 2013, the Company had $198,000 in prepaid assets (prepaid clinical, material,  manufacturing and other–related parties), $383,000 in accounts payable–related parties, and $2.8 million in accrued and other liabilities (accrued clinical, manufacturing and other–related parties), all reflected on the Company’s consolidated balance sheet associated with Medpace. The Company recognized $24.1 million, $4.7 million and $1.0 million during years ended December 31, 2014, 2013 and 2012, respectively, for services rendered by Medpace within research and development expense in the consolidated statements of operations. Additionally, the Company recognized $0.5 million of interest expense for the year ended December 31, 2013 associated with extended payment arrangement with Medpace. The Company also has an agreement with Medpace which provides for a minimum fee commitment of $35.0 million for clinical trial services which is further discussed in Note 8. As of December 31, 2014, $20.7 million of the services related to the fee commitment under this agreement has been performed or paid for.
	Recruiting Services
	One member of the Board of Directors was the chief executive officer of a company that provided recruiting services to the Company. As such, the recruiting services provided were deemed to be related party transactions. As of December 31, 2014, the Company had $90,000 in accounts payable-related parties reflected on the Company’s consolidated balance sheet. As of December 31, 2013, there were no such balances in the Company’s consolidated balance sheet. The Company recorded in research and development expense in its consolidated statements of operations, $241,000, $35,000 and $163,000 for the years ended December 31, 2014, 2013 and 2012, respectively, for services rendered by the recruiting company. The Company recorded in general and administrative expense in its consolidated statements of operations, $597,000, $18,000 and $61,000 for the year ended December 31, 2014, 2013 and 2012, respectively, for services rendered by the recruiting company.
	Convertible Notes — Related Parties
	In the third quarter of 2011, the Company entered into the 2011 Notes with certain investors, including some members of the Board of Directors and their affiliated companies and some members of management, for a total aggregate amount of $10.4 million (see Note 7) and issued the 2011 Warrants B to purchase shares of the Company’s preferred stock at an exercise price of $0.0167 per share (see Note 9). As such, the $9.3 million of the total aggregate amount of the 2011 Notes were considered related party transactions. In January 2012, as a result of the Series B convertible preferred stock financing event, the $9.3 million of the 2011 Notes and accrued interest of $193,000 were automatically converted into 1,358,086 shares of Series B convertible preferred stock at the issuance price of $6.9749 per share, the amount paid by the other Series B investors, and the 2011 Warrant B became exercisable for warrants to purchase 305,927 shares of Series B convertible preferred stock. In the third quarter of 2013, the Company entered into Bridge Loans with certain investors, including existing stockholders, some members of the Board of Directors and their affiliated companies and some members of management, for a total aggregate amount of $10.0 million and issued the 2013 Warrants to purchase shares of the Company’s preferred stock at an exercise price of $0.0167 per share. As such, $7.1 million of the total aggregate amount of the Bridge Loans were from related parties. As of December 31, 2013, the carrying value of the Bridge Loans was $3.1 million, net of debt discount. In May 2014, the Company completed a preferred stock financing and contemporaneously the Bridge Loans and the related accrued interest were automatically converted into Series C preferred stock (see Note 7). For the years ended December 31, 2014, 2013 and 2012, the Company recognized $2.7 million, $3.3 million and $1.1 million, respectively, of interest expense related to the debt and the amortization of the debt discount in the Company’s consolidated statements of operations.
	InteKrin Acquisition
	In February 2014, the Company completed the acquisition of the InteKrin for total consideration of $5.0 million (see Note 6). Mr. Dennis M. Lanfear, the chief executive officer of the Company was the chairman of the board and acting president of InteKrin at the time of the acquisition. As such, the InteKrin acquisition was a related party transaction. Mr. Lanfear also owns 10% of the outstanding securities of InteKrin Russia.
	Other Assets – Related Party
	In December 2014, the Company entered into an agreement with an officer of the Company, in which the officer irrevocably transferred his rights to a certain number of shares with an aggregate value of $1.7 million.  This transaction is expected to settle on or about, July 10, 2015.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	16	Subsequent Events
	In March 2015, the Company achieved the first dosing of a human subject in a phase 2 clinical trial for INT-131 in multiple sclerosis patients, triggering the obligation to settle the contingent earn-out payment to InteKrin stockholders (see Note 6).  Accordingly, the Company issued 358,384 shares of its common stock and recorded a total contingent consideration liability of $9.8 million in which the Company immediately reclassified to equity.

Supplementary_Data_Quarterly_F

Supplementary Data - Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	17	Supplementary Data – Quarterly Financial Data (Unaudited)
	The following table presents certain unaudited consolidated quarterly financial information for each of the quarters ended December 31, 2014 and 2013:
			2014 Quarter End
	(in thousands, except per share data)		31-Mar			30-Jun			30-Sep			31-Dec
	Total revenue		$	3,596		$	4,965		$	16,052		$	6,493
	Total operating expenses			17,357			22,903			22,475			33,053
	Net loss			(25,170	)		(25,070	)		(7,914	)		(29,023	)
	Net loss attributable to Coherus			(25,170	)		(24,957	)		(7,872	)		(29,134	)
	Net loss per share attributable to Coherus, basic and diluted			(6.04	)		(5.96	)		(1.79	)		(1.47	)
			2013 Quarter End
			31-Mar			30-Jun			30-Sep			31-Dec
	Total revenue		$	506		$	507		$	506		$	1,232
	Total operating expenses			9,945			9,791			7,289			11,719
	Net loss and net loss attributable to Coherus			(8,862	)		(8,709	)		(21,473	)		(14,591	)
	Net loss per share, basic and diluted			(3.14	)		(2.80	)		(6.23	)		(3.68	)

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Consolidation	Basis of Consolidation
	The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). The accompanying consolidated financial statements include the accounts of Coherus and its wholly owned subsidiaries as of December 31, 2014: Coherus Intermediate Corp, InteKrin Therapeutics, Inc. (“InteKrin”), and its 82.5% majority owned subsidiary of InteKrin Russia. Unless otherwise specified, references to the Company are references to Coherus and its consolidated subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation.
Reverse Stock Split	Reverse Stock Split
	In October 2014, the Company’s board of directors and its stockholders approved the filing of an amended and restated certificate of incorporation to effect a reverse split of the then outstanding shares of the Company’s preferred stock and common stock on a 1-for-1.667 basis (the “Reverse Stock Split”). All information in these financial statements related to the number of shares, price per share and per share amounts of stock, and shares issuable under stock options and warrants have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was effectuated on November 5, 2014. The Company filed an amended and restated certificate of incorporation in Delaware on November 5, 2014 that automatically effectuated the Reverse Stock Split without any further action required.
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuations of the convertible preferred stock warrant liability and embedded derivative instruments, valuation of deferred tax assets, convertible preferred stock, clinical trial accruals, revenue recognition period, as well as certain accrued liabilities. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
Foreign Currency	Foreign Currency
	The functional currency of InteKrin Russia, which the Company acquired in February 2014, is the Russian Ruble. Accordingly, the financial statements of this subsidiary are translated into U.S. dollars using appropriate exchange rates. Unrealized gains or losses on translation are recognized in accumulated other comprehensive loss in the condensed consolidated balance sheet.
	For the years ended December 31, 2014, 2013 and 2012, the foreign exchange gains and losses recorded in other income (expense), net in the consolidated statements of operations was a $671,000 gain, a $34,000 loss and $0, respectively.
Segment Reporting	Segment Reporting
	The Company operates and manages its business as one reportable and operating segment, which is the business of developing and commercializing biosimilar products, and small molecules as part of the InteKrin acquisition (see Note 6). The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. Long-lived assets are primarily maintained in the United States of America.
	The following table summarizes revenue by geographic region:
			Year Ended December 31,
			2014			2013		2012
	United States		$	28,481		$	726	—
	Rest of world			2,625			2,025		1,899
	Total revenue		$	31,106		$	2,751	$	1,899
Deferred Offering Costs	Deferred Offering Costs
	Deferred offering costs, which primarily consisted of direct incremental legal and accounting fees relating to the IPO, were capitalized in other assets until the completion of the IPO. These deferred offering costs were reclassified to additional paid-in capital upon the closing of the IPO in November 2014. There were no deferred offering costs capitalized as of December 31, 2013.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investment with original maturities of 90 days or less at the date of purchase to be cash and cash equivalents.
Restricted Cash	Restricted Cash
	Restricted cash consists of cash held in a money market account with a bank, and which is collateral against the Company’s corporate credit cards.
Concentration of Credit Risk	Concentration of Credit Risk
	The Company’s financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank accounts which at times exceed federally insured limits. The Company attempts to minimize the risks related to cash and cash equivalents by investing in money markets with a broad and diverse range of financial instruments. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. The Company also maintains restricted cash in money market funds that invest primarily in U.S. Treasury securities. The Company has not recognized any losses from credit risks on such accounts during any of the periods presented. The Company believes it is not exposed to significant credit risk on its cash and money market funds.
	Customer Concentration
	Customers whose revenue accounted for 10% or more of total revenues were as follows:
			Year Ended December 31,
			2014		2013	2012
	Daiichi Sankyo - related party		*		74%	100%
	Baxter		92%		26%	—
	*	less than 10%
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis.
Property and Equipment	Property and Equipment
	Property and equipment are stated at cost less accumulated depreciation and amortization. Maintenance and repairs are charged to expense as incurred, and costs of improvements are capitalized. Depreciation and amortization is recognized using the straight-line method over the following estimated useful lives:
	Computer equipment and software		3 years
	Furniture and fixtures		5 years
	Machinery and equipment		5 years
	Leasehold improvements		Shorter of lease term or useful life
Impairment of Long Lived Assets and Acquired Intangible Asset	Impairment of Long Lived Assets and Acquired Intangible Asset
	The Company reviews long-lived assets, including property and equipment, and indefinite-lived intangible, for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value.  As of December 31, 2014, there have been no such impairments.
	Acquired IPR&D represents the fair value assigned to research and development assets that have not reached technological feasibility.  The Company reviews amounts capitalized as acquired IPR&D for impairment at least annually, and whenever events or changes in circumstances indicate that the carrying value of the assets might not be recoverable. If the carrying value of the acquired IPR&D exceeds its fair value, then the intangible asset is written-down to its fair value. As of December 31, 2014, there have been no such impairments. Once the product candidate derived from the indefinite-lived intangible asset has been developed and commercialized, the useful life will be determined, and the carrying value of the finite-lived asset will be amortized prospectively over that estimated useful life. Alternatively, if the product candidate is abandoned, the carrying value of the intangible will be charged to research and development expense.
Goodwill	Goodwill
	Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired. The Company tests goodwill for impairment at least annually or more frequently if events or changes in circumstances indicate that this asset may be impaired. The goodwill test is based on our single operating segment and reporting unit structure.
	The Company compares the fair value of its reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company would need to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of the reporting unit’s goodwill exceeds its implied fair value, then the Company would record an impairment loss equal to the difference. No goodwill impairment was identified through December 31, 2014.
Convertible Preferred Stock	Convertible Preferred Stock
	The Company recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance. In the event of a change of control of the Company, proceeds received from the sale of such shares would have been distributed in accordance with the liquidation preferences set forth in the Company’s Amended and Restated Certificate of Incorporation unless the holders of convertible preferred stock have converted their shares of convertible preferred stock into shares of common stock. Therefore, convertible preferred stock was classified outside of stockholders’ equity (deficit) on the consolidated balance sheets as events triggering the liquidation preferences were not solely within the Company’s control. The Company elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. In November 2014, as a result of the Company’s IPO, all shares of convertible preferred stock were converted into shares of common stock on a one-for-one basis.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability
	The Company classified warrants exercisable for shares of the Company’s Series A and Series B convertible preferred stock as derivative liabilities and adjusted their carrying value to fair value at the end of each reporting period as long as such warrants were outstanding. At the end of each reporting period, changes in the fair value of the convertible preferred stock warrant liability during the period were recorded as a component of other income (expense), net, in the consolidated statements of operations.
Derivative Liability	Derivative Liability
	The Company has a derivative liability related to the contingent consideration associated with the acquisition of InteKrin. There are two contingent payments payable upon the achievement of certain events: (i) the completion of the first dosing of a human subject in the first Phase 2 clinical trial for InteKrin, (“Earn-Out Payment”) and (ii) upon the execution of any license, sublicense, development, collaboration, joint venture, partnering or similar agreement between the Company and the third party (“Compound Transaction Payment”). The derivative related to the contingent consideration is accounted for as a liability and remeasured to fair value as of each balance sheet date and the related remeasurement adjustment is recognized as other income (expense), net in the consolidated statements of operations. The Company determined the fair value of the two contingent consideration scenarios (the Earn-Out Payment and the Compound Transaction Payment) using a probability-weighted discounted cash flow approach. A probability-weighted value was determined by summing the probability of achieving a contingent payment threshold by the respective contingent payments. The expected cash flows were discounted at a rate selected to capture the risk of achieving the contingent payment thresholds and earning the contingent payment. This risk is comprised of InteKrin’s continued development, a specific risk factor associated with meeting the contingent consideration threshold and related payout, and counterparty risk associated with the payment of the contingent consideration.
Embedded Derivative Liability	Embedded Derivative Liability
	The Company recorded derivative instruments related to redemption features embedded within the convertible notes when such notes were outstanding. The embedded derivatives were accounted for as a liability and were remeasured to fair value as of each balance sheet date when such notes were outstanding, with the related remeasurement adjustment being recognized as a component of other income (expense), net in the consolidated statements of operations.
Accrued Research and Development Expenses	Accrued Research and Development Expenses
	Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the actual costs through monitoring patient enrollment and discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
Revenue Recognition	Revenue Recognition
	The Company recognizes revenue when persuasive evidence of an arrangement exists; transfer of technology has been completed, services have been performed or products have been delivered; the fee is fixed and determinable; and collection is reasonably assured.
	The Company enters into collaboration and license agreements for the development and commercialization of biosimilar products. The Company’s performance obligations under the terms of these agreements may include (i) transfer of intellectual property rights (licenses), (ii) providing research and development services, (iii) the manufacture of drug materials for development purposes and (iv) participation on certain committees with the collaborators. Payments to the Company under these agreements may include nonrefundable upfront license fees, payments for research and development services, payments for the manufacture of drug materials, payments based upon the achievement of defined collaboration objectives and royalties on product sales. Under these agreements, the Company may convey the right to sell products resulting from the collaborative efforts of the parties in specific geographic territories.
	For revenue agreements with multiple elements, the Company identifies the deliverables included within the agreement and evaluates which deliverables may represent separate units of accounting based on the achievement of certain criteria, including whether the delivered element has stand-alone value to the collaborator. Deliverables under the arrangement are a separate unit of accounting if (i) the delivered item has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item and delivery or performance of the undelivered items are considered probable and substantially within the Company’s control.
	The Company determines how to allocate arrangement consideration to identified units of accounting based on the selling price hierarchy provided under the relevant guidance. The selling price used for each unit of accounting is based on vendor-specific objective evidence, if available, third party evidence if vendor-specific objective evidence is not available or estimated selling price if neither vendor-specific nor third-party evidence is available. Management may be required to exercise considerable judgment in determining whether a deliverable is a separate unit of accounting and in estimating the selling prices of identified units of accounting under its agreements.
	Upfront payments received in connection with licenses of the Company’s technology rights are deferred if facts and circumstances dictate that the license does not have stand-alone value. Such payments are recognized as license revenue over the estimated period of performance that is generally consistent with the terms of the research and development obligations contained in the specific collaboration and license agreement. The Company regularly reviews the estimated period of performance based on the progress made under each arrangement. Amounts received as funding of research and development activities are recognized as revenue if the collaboration arrangement involves the sale of the Company’s research or development services. However, such funding is recognized as a reduction in research and development expense when the Company engages in a research and development project jointly with another entity, with both entities participating in project activities and sharing costs and potential benefits of the arrangement.
	Payments that are contingent upon the achievement of a substantive milestone are recognized in their entirety in the period in which the milestone is achieved, assuming all other revenue recognition criteria are met. Milestones are defined as an event that can only be achieved based on the Company’s performance and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones under accounting guidance. The Company’s evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the Company’s performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (b) the consideration relates solely to past performance and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
	Other contingent payments in which a portion of the payment is refundable or adjusts based on future performance or non-performance (e.g., through a penalty or claw-back provision) are not considered to relate solely to the Company’s past performance, and therefore, not considered substantive. Non-substantive contingent payments are classified as deferred revenue if they are ultimately expected to result in revenue recognition. The Company recognizes non-substantive contingent payments over the remaining estimated period of performance once the specific objective is achieved. Any portion of the non-substantive contingent payments which may be required to be refunded to the collaborator are not included in deferred revenue and instead are reflected as contingent liability to collaborator on the consolidated balance sheets.
	Contingent payments associated with the achievement of specific objectives in certain contracts that are not considered substantive because the Company does not contribute effort to the achievement of such milestones are recognized as revenue upon achievement of the objective, as long as there are no undelivered elements remaining and no continuing performance obligations by the Company, assuming all other revenue recognition criteria are met.
	The government contract with the Russian government is an agreement that provides the Company with payments for certain types of expenditures in return for research and development activities over a contractually defined period. Revenue from the government contract is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the funds received are not refundable and applicable conditions under the government contract have been met. Funds received in advance are recorded as deferred revenue.
Research and Development Expense	Research and Development Expenses
	Research and development costs are charged to expenses as incurred. Research and development expenses include, among other costs, salaries and other personnel-related costs, consultant fees, preclinical costs, cost to manufacture drug candidates and clinical supplies, laboratory supplies costs and facility-related costs. Costs incurred under agreements with third parties are charged to expense as incurred in accordance with the specific contractual performance terms of such agreements. Costs of third parties include costs associated with preclinical and clinical support activities. In certain cases, amounts received as reimbursement of research and development activities from the Company’s collaborators are recognized as a reduction in research and development expense when the Company engages in a research and development project jointly with another party, with both parties incurring costs while actively participating in project activities and both parties sharing costs and potential benefits of the arrangement. Costs incurred under the arrangements where the Company provides research services approximate the amount of revenues recorded. Advance payments for goods or services to be received in the future to be utilized in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are received.
Share-Based Compensation	Stock-Based Compensation
	The Company measures the cost of equity-based service awards based on the grant-date fair value of the award, and recognizes the cost of such awards straight-line over the vesting period. Because non-cash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates.
	The Company accounts for equity instruments issued to nonemployees using the fair value approach. These equity instruments consist of stock options and restricted common stock, which are valued using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized as the equity instruments are earned. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest.
	The Company utilizes the Black-Scholes option-pricing model for estimating fair value of its stock options and restricted stock granted. Option valuation models, including the Black-Scholes option-pricing model, require the input of highly subjective assumptions, and changes in the assumptions used can materially affect the grant-date fair value of an award. These assumptions include the risk-free rate of interest, expected dividend yield, expected volatility, the expected life of the award, and estimated forfeitures.
Income Taxes	Income Taxes
	The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.
	The Company recognizes uncertain income tax positions at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. The Company does not expect its unrecognized tax benefits to change significantly over the next twelve months.
	The Company’s policy is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had accrued no amounts for interest and penalties related to income tax matters in the Company’s consolidated balance sheets at December 31, 2014 and 2013.
Comprehensive Loss	Comprehensive Loss
	Comprehensive loss is composed of two components: net loss and other comprehensive income (loss). Other comprehensive income (loss) refers to gains and losses that under U.S. GAAP are recorded as an element of stockholders’ equity (deficit), but are excluded from net loss. The Company’s other comprehensive loss included foreign currency translation adjustments for the year ended December 31, 2014.
Net Loss per Share Attributable to Coherus	Net Loss per Share Attributable to Coherus
	Basic net loss per share attributable to Coherus is calculated by dividing the net loss attributable to Coherus by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive common shares. Since the Company was in a loss position for all periods presented, basic net loss per share attributable to Coherus is the same as diluted net loss per share attributable to Coherus as the inclusion of all potential dilutive common shares would have been anti-dilutive. Shares of founders’ common stock subject to repurchase are excluded from the calculation of weighted average shares as the vesting of such shares is contingent upon continued services being rendered by such holders.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which converges the FASB and the International Accounting Standards Board standards on revenue recognition. Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variable consideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. This guidance is effective for the fiscal years and interim reporting periods beginning after December 15, 2016, at which time the Company may adopt the new standard under the full retrospective method or the modified retrospective method. Early adoption is not permitted. The Company is currently evaluating the impact that the adoption of ASU 2014-09 will have on its consolidated financial statements and related disclosures.
	In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. In doing so, companies will have reduced diversity in the timing and content of footnote disclosures than under today’s guidance. ASU 2014-15 is effective for the Company in the first quarter of 2016 with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2014-15 will have on its consolidated financial statements and related disclosures.
	The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or no material effect is expected on the consolidated financial statements as a result of future adoption.

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Revenue by Geographical Region	The following table summarizes revenue by geographic region:
			Year Ended December 31,
			2014			2013		2012
	United States		$	28,481		$	726	—
	Rest of world			2,625			2,025		1,899
	Total revenue		$	31,106		$	2,751	$	1,899
Summary of Customers Revenue Accounted for 10% or More of Total Revenue	Customers whose revenue accounted for 10% or more of total revenues were as follows:
			Year Ended December 31,
			2014		2013	2012
	Daiichi Sankyo - related party		*		74%	100%
	Baxter		92%		26%	—
	*	less than 10%
Schedule of Estimated Useful Lives of Property Plant and Equipment	Property and equipment are stated at cost less accumulated depreciation and amortization. Maintenance and repairs are charged to expense as incurred, and costs of improvements are capitalized. Depreciation and amortization is recognized using the straight-line method over the following estimated useful lives:
	Computer equipment and software		3 years
	Furniture and fixtures		5 years
	Machinery and equipment		5 years
	Leasehold improvements		Shorter of lease term or useful life

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets and Liabilities Measured on a Recurring Basis	Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements are as follows (in thousands):
		Fair Value Measurements
		31-Dec-14
		Total			Level 1		Level 2		Level 3
	Assets:
	Money market funds	$	147,952		$	147,952	$	—	$	—
	Restricted cash (money market funds)		60			60		—		—
	Total financial assets	$	148,012		$	148,012	$	—	$	—
	Liabilities:
	Contingent consideration	$	6,495		$	—	$	—	$	6,495
		Fair Value Measurements
		31-Dec-13
		Total			Level 1		Level 2		Level 3
	Assets:
	Restricted cash (money market funds)	$	50		$	50	$	—	$	—
	Liabilities:
	Convertible preferred stock warrant liability	$	24,251		$	—	$	—	$	24,251
Convertible Preferred Stock Warrant Liability and Embedded Derivatives | Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets and Liabilities Measured on a Recurring Basis	The fair values of the convertible preferred stock warrant liability and embedded derivatives were based on the following assumptions at the respective issuance dates and as of December 31, 2013.  These instruments were not outstanding as of December 31, 2014:
		Jul-13		August and	December 31,
		Issuance		Sep-13	2013
				Issuance
	Discount rate	30%		30%	30%
	Weighted-average scenario probabilities:
	New equity financing	25%		65%	63%
	New equity financing at lower valuation then previous financing	5%		5%	7%
	Initial public offering	5%		5%	10%
	Change of control	25%		5%	—
	Maturity	40%		20%	20%
Convertible Preferred Stock Warranty Liability | Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets and Liabilities Measured on a Recurring Basis	The following table sets forth a summary of the changes in the estimated fair value of the convertible preferred stock warrants (in thousands):
		December 31,
		2014			2013
	Balance, beginning of year	$	24,251		$	1,738
	Warrants issued in connection with notes payable	—				9,950
	Initial fair value of the warrants issued in excess of debt	—				3,669
	proceeds recognized in other income (expense), net
	Warrants exercised		(40,150	)	—
	Change in fair value of convertible preferred stock warrant liability		15,899			8,894
	Balance, end of year	$	—		$	24,251
Contingent Consideration | Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets and Liabilities Measured on a Recurring Basis	The following table sets forth a summary of changes in the estimated fair value of the contingent consideration (in thousands):
	Balance as of February 12, 2014 (acquisition date)	$	1,310
	Change in fair value of the contingent consideration liability		5,185
	Balance as of December 31, 2014	$	6,495
Derivative Instrument | Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets and Liabilities Measured on a Recurring Basis	The following table sets forth a summary of the changes in the estimated fair value of the derivative instrument (in thousands):
		December 31,
		2013
	Balance, beginning of year	$	—
	Initial fair value of the embedded derivative issued in excess		4,096
	of debt proceeds recognized in other income (expense), net
	Change in fair value of embedded derivative		(4,096	)
	Balance, end of year	$	—

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Prepaid Assets	Prepaid assets are as follows (in thousands):
		December 31,			December 31,
		2014			2013
	Prepaid clinical, material, manufacturing and other - related parties	$	5,990		$	3,177
	Prepaid clinical, material and  manufacturing		12,149			1,758
	Prepaid other		2,346			753
	Prepaid assets	$	20,485		$	5,688
Schedule of Property and Equipment, Net	Property and equipment, net are as follows (in thousands):
		December 31,			December 31,
		2014			2013
	Machinery and equipment	$	4,317		$	2,051
	Computer equipment and software		286			79
	Furniture and fixtures		288			147
	Leasehold improvements		399			91
	Construction in progress		474			—
	Total property and equipment		5,764			2,368
	Accumulated depreciation and amortization		(1,292	)		(625	)
	Property and equipment, net	$	4,472		$	1,743
Schedule of Accrued Liabilities	Accrued liabilities are as follows (in thousands):
		December 31,			December 31,
		2014			2013
	Accrued clinical, manufacturing and other - related parties	$	2,997		$	2,792
	Accrued compensation		3,435			1,549
	Accrued professional and consulting fees		252			995
	Accrued other		4,547			1,922
	Accrued liabilities	$	11,231		$	7,258

Collaboration_and_License_Agre1

Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2014
Collaboration And License Agreements [Abstract]
Schedule of Revenue Related to Collaboration and License Agreements	The Company recognized revenue related to the collaboration and license agreements for the periods presented as follows (in thousands):
		Year Ended December 31,
		2014		2013		2012
	Daiichi Sankyo - related party	$	1,893	$	2,025	$	1,899
	Baxter		28,481		726		—
	Total collaboration and license revenue	$	30,374	$	2,751	$	1,899

Acquisition_of_InteKrin_Therap1

Acquisition of InteKrin Therapeutics, Inc. (Tables)	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Fair Value of Assets Acquired and Liabilities Assumed	The following table summarizes the original fair value of the assets acquired and liabilities assumed (in thousands):
	Cash	$	2,335
	Prepaid and other assets		107
	Accounts payable and other current liabilities		(1,027	)
	In-process research and development		2,620
	Goodwill		943
	Total consideration	$	4,978

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Facilities	The future minimum lease payments for these facilities as of December 31, 2014 are as follows (in thousands):
	Year ending December 31,
	2015	$	1,082
	2016		1,117
	2017		404
	Total minimum lease payments	$	2,603

Convertible_Preferred_Stock_Wa1

Convertible Preferred Stock Warrants (Tables)	12 Months Ended
	Dec. 31, 2014
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock Warrants and Related Estimated Fair Values	The following table sets forth a summary of the convertible preferred stock warrants and the related estimated fair values as of December 31, 2013 (in thousands, except share data). No convertible preferred stock warrants were outstanding as of December 31, 2014:
		31-Dec-13
		Shares Underlying			Estimated Fair
		the Warrants			Value
	Warrants to purchase Series A convertible		63,923		$	170
	preferred stock — 2011 Warrants A
	Warrants to purchase Series B convertible		295,101			1,122
	preferred stock — 2011 Warrants B
	2013 Warrants		4,279,620			22,959
	Total		4,638,644		$	24,251
Summary of Estimated Fair Value of Warrants Issuance Based on Probability Weighted Present Values with Qualifying Event Scenarios	The estimated fair value of the warrants at issuance was $2.7 million based on probability-weighted present values of the warrants under the qualifying event scenarios with the follows assumptions:
	Issuance Date	Next Financing Event in		Change of Control, IPO or
		Which the Company		Maturity Date
		Issued Newly Authorized
		Shares of Preferred Stock
	21-Jul-11	35%		65%
	31-Aug-11	50%		50%
	31-Oct-11	75%		25%
	29-Nov-11	85%		15%
	21-Dec-11	90%		10%

Convertible_Preferred_Stock_an1

Convertible Preferred Stock and Stockholders Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2014
Equity Method Investment Summarized Financial Information Liabilities And Equity [Abstract]
Schedule of Outstanding Convertible Preferred Stock	As of December 31, 2013, the outstanding convertible preferred stock was as follows (in thousands, except share data):
	31-Dec-13	Shares Authorized		Shares Issued		Carrying Value		Liquidation
				and Outstanding				Preference
	Series A		1,800,000		972,330	$	1,191	$	1,216
	Series B		26,290,997		8,181,576		53,504		57,066
			28,090,997		9,153,906	$	54,695	$	58,282

Stock_Option_Plans_and_StockBa1

Stock Option Plans and Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Summary of Non-Vested Restricted Stock	A summary of the Company’s non-vested restricted stock for the periods is as follows:
		Number of
		Shares
	Non-vested as of December 31, 2011		3,644,858
	Vested		(1,207,062	)
	Repurchased by the Company		(286,817	)
	Non-vested as of December 31, 2012		2,150,979
	Vested		(1,387,650	)
	Non-vested as of December 31, 2013		763,329
	Vested		(742,084	)
	Non-vested as of December 31, 2014		21,245
Summary of Option Activities under 2014 and 2010 Plans	The following table sets forth the summary of option activities under the 2014 and 2010 Plans:
					Options Outstanding
		Shares Available			Number of			Weighted-Average
		for Grant			Options			Exercise Price
	Balances at December 31, 2011		14,999			974,797		$	0.358
	Authorized		1,520,830			—			—
	Granted - at fair value		(611,285	)		611,285			2.084
	Exercised		—			(22,307	)		0.008
	Forfeited		28,680			(28,680	)		0.008
	Balances at December 31, 2012		953,224			1,535,095		$	1.057
	Authorized		1,586,570			—			—
	Granted - at fair value		(853,244	)		853,244			2.084
	Granted - below fair value		(786,018	)		786,018			1.417
	Exercised		—			(3,248	)		2.084
	Forfeited		123,713			(123,713	)		1.271
	Balances at December 31, 2013		1,024,245			3,047,396		$	1.427
	Authorized		4,399,580			—			—
	Granted - at fair value		(614,062	)		614,062			13.907
	Granted - below fair value		(2,703,441	)		2,703,441			1.833
	Exercised		—			(48,414	)		1.144
	Forfeited		546,178			(546,178	)		1.831
	Balances at December 31, 2014		2,652,500			5,770,307		$	2.909
Summary of Additional Information Related to Status of Options
	Additional information related to the status of options as of December 31, 2014 is summarized as follows:
		Number of Options			Weighted-Average			Weighted-Average			Aggregate Intrinsic
					Exercise Price			Contractual Terms			Value (in thousands)
								(Years)
	Options outstanding		5,770,307		$	2.909			8.65		$	77,383
	Options vested and expected to vest		5,764,337		$	2.909			8.64		$	77,303
	Options vested		2,364,401		$	1.483			8.49		$	35,080
	Options exercisable		2,365,651		$	1.482			7.9		$	35,101
Schedule of Weighted Average Assumptions Used to Value Options Granted to Employees	The weighted average assumptions used to value options granted to employees under the Plan during the years ended December 31, 2014, 2013 and 2012 were as follows:
		Year Ended December 31,
		2014			2013			2012
	Expected term (years)		6.5			5.51			6.04
	Expected volatility		99	%		108	%		110	%
	Risk-free interest rate		2.05	%		1.23	%		0.93	%
	Expected dividend yield		0	%		0	%		0	%
Schedule of Stock-Based Compensation Expense Related to Options	The stock-based compensation expense recorded related to options granted to employees was as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Research and development	$	1,580		$	431		$	30
	General and administrative		3,934			309			65
		$	5,514		$	740		$	95
Restricted Common Stock (Founders Shares)
Schedule of Stock-Based Compensation Expense	The stock-based compensation expense recorded related to the founder’s shares was as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Research and development	$	1,547		$	227		$	232
	General and administrative		4			1,054			110
		$	1,551		$	1,281		$	342

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Reconciliation of Statutory U.S. Federal Rate	A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:
		Year Ended December 31,
		2014			2013			2012
	Percent of pre-tax income:
	U.S. federal statutory income tax rate		34	%		34	%		34	%
	State taxes, net of federal benefit		(1.65	)		3.97			6.68
	Permanent items		(10.80	)		(12.40	)		5.65
	Research and development credit		3.11			4.53			—
	Net operating loss		0.01			—			—
	InteKrin purchase price allocation		0.73			—			—
	Other		0.02			—			(0.17	)
	Change in valuation allowance		(25.42	)		(30.10	)		(46.16	)
	Effective income tax rate		—	%		—	%		—	%
Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets as of December 31, 2014 and 2013 consist of the following (in thousands):
		December 31,
		2014			2013
	Net operating loss carryforwards	$	34,463		$	27,524
	Research and development credits		6,032			2,823
	Depreciation and amortization		854			26
	Stock-based compensation		1,428			82
	Other accruals		940			626
	Deferred revenue		12,762			2,413
	Gross deferred tax assets		56,479			33,494
	In-process research and development		(892	)		-
	Gross deferred tax liabilities		(892	)		-
	Total net deferred tax asset		55,587			33,494
	Less valuation allowance		(55,587	)		(33,494	)
	Net deferred tax assets	$	—		$	—
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2014 and 2013 is as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Balance at beginning of year	$	749		$	73		$	14
	Additions based on tax positions related to current year		861			319			59
	Additions for tax positions of prior years		2,206			357			—
	Balance at end of year	$	3,816		$	749		$	73

Net_Loss_Per_Share_Attributabl1

Net Loss Per Share Attributable to Coherus (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share Attributable to Coherus	The following table sets forth the computation of the basic and diluted net loss per share attributable to Coherus (in thousands, except share and per share data):
			Years Ended December 31,
			2014			2013			2012
	Numerator:
	Net loss attributable to Coherus		$	(87,133	)	$	(53,635	)	$	(33,018	)
	Denominator:
	Weighted-average common shares outstanding			8,520,100			4,828,214			4,963,883
	Less: weighted-average unvested common shares subject to			(333,571	)		(1,496,194	)		(2,881,261	)
	repurchase
	Weighted-average number of shares used in computing net loss per			8,186,529			3,332,020			2,082,622
	share attributable to Coherus, basic and diluted
	Net loss per share attributable to Coherus, basic and diluted		$	(10.64	)	$	(16.10	)	$	(15.85	)
	·	Shares were excluded as such shares represent restricted common stock (founders’ shares) which is vesting contingently upon the holders’ continued services to the Company.
Outstanding Dilutive Potential Shares Excluded from Calculation of Diluted Net Loss Per Share Attributable to Coherus	The following outstanding dilutive potential shares have been excluded from the calculation of diluted net loss per share attributable to Coherus due to their anti-dilutive effect:
			December 31,
			2014			2013			2012
	Stock options outstanding			5,770,307			3,047,396			1,535,095
	Convertible preferred stock			—			9,153,906			9,153,906
	Convertible preferred stock warrants			—			4,638,644			359,024
	Total			5,770,307			16,839,946			11,048,025

Supplementary_Data_Quarterly_F1

Supplementary Data - Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following table presents certain unaudited consolidated quarterly financial information for each of the quarters ended December 31, 2014 and 2013:
		2014 Quarter End
	(in thousands, except per share data)	31-Mar			30-Jun			30-Sep			31-Dec
	Total revenue	$	3,596		$	4,965		$	16,052		$	6,493
	Total operating expenses		17,357			22,903			22,475			33,053
	Net loss		(25,170	)		(25,070	)		(7,914	)		(29,023	)
	Net loss attributable to Coherus		(25,170	)		(24,957	)		(7,872	)		(29,134	)
	Net loss per share attributable to Coherus, basic and diluted		(6.04	)		(5.96	)		(1.79	)		(1.47	)
		2013 Quarter End
		31-Mar			30-Jun			30-Sep			31-Dec
	Total revenue	$	506		$	507		$	506		$	1,232
	Total operating expenses		9,945			9,791			7,289			11,719
	Net loss and net loss attributable to Coherus		(8,862	)		(8,709	)		(21,473	)		(14,591	)
	Net loss per share, basic and diluted		(3.14	)		(2.80	)		(6.23	)		(3.68	)

Organization_and_Operations_Ad

Organization and Operations - Additional Information (Details) (USD $)	12 Months Ended	0 Months Ended
	Dec. 31, 2014	Nov. 12, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2014	Nov. 06, 2014
	Segments
Organization And Operations [Line Items]
Number of operating segments	1
Common stock, shares issued	33,257,978		4,837,715
Net proceeds from issuance of common stock	$85,419,000
Offering expense	4,307,000
Common stock, shares authorized	300,000,000
Preferred stock, shares authorized	5,000,000
Common stock, par value	$0.00		$0.00
Preferred stock, par value	$0.00		$0.00
Accumulated deficit	186,725,000		99,592,000
Cash and cash equivalents	150,392,000		39,554,000	14,548,000	7,684,000
Amended and Restated Certificate of Incorporation
Organization And Operations [Line Items]
Common stock, shares authorized		300,000,000
Preferred stock, shares authorized		5,000,000
Common stock, par value		$0.00
Preferred stock, par value		$0.00
Common Stock
Organization And Operations [Line Items]
Stock issued for warrant exercised						553,274
IPO
Organization And Operations [Line Items]
Share price							$13.50
Common stock, shares issued		6,803,702
Net proceeds from issuance of common stock		91,800,000
Underwriting discounts and commissions		6,400,000
Offering expense		5,200,000
Proceeds from issuance of common stock, net of offering expense		$80,200,000
Conversion of convertible preferred stock to common stock in connection with initial public offering, Shares		21,316,519
Stock issued for warrant exercised		185,302
IPO | Amended and Restated Certificate of Incorporation
Organization And Operations [Line Items]
Common stock, shares authorized		300,000,000
Preferred stock, shares authorized		5,000,000
Common stock, par value		$0.00
Preferred stock, par value		$0.00
IPO | Common Stock
Organization And Operations [Line Items]
Conversion of convertible preferred stock to common stock in connection with initial public offering, Shares	21,316,519
Stock issued for warrant exercised		491,580
Over Allotment of Option
Organization And Operations [Line Items]
Common stock, shares issued		507,402

Basis_of_Presentation_and_Summ3

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 08, 2014
	Segments
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Reverse stock split description	1-for-1.667
Foreign exchange gain (loss)	$671,000	($34,000)	$0
Number of reportable segment	1
Number of operating segments	1
Deferred offering costs		0
Convertible preferred stock conversion, description	In November 2014, as a result of the Companybs IPO, all shares of convertible preferred stock were converted into shares of common stock on a one-for-one basis.
Income tax examination, description	less than a 50%
Unrecognized tax benefits, interest and penalties accrued related to income tax matters	0	0
InteKrin Therapeutics Inc
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Impairment of goodwill	0
InteKrin Therapeutics Inc | In Process Research and Development
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Impairment of long lived assets	0
Impairment of intangible assets excluding goodwill	$0
RUSSIA | InteKrin Therapeutics Inc | Coherus Intermediate Corp, InteKrin Therapeutics, Inc.
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Controlling interest, ownership percentage by parent	82.50%			82.50%

Basis_of_Presentation_and_Summ4

Basis of Presentation and Summary of Significant Accounting Policies - Summary of Revenue by Geographical Region (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$6,493	$16,052	$4,965	$3,596	$1,232	$506	$507	$506	$31,106	$2,751	$1,899
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									28,481	726
Rest of World
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									$2,625	$2,025	$1,899

Basis_of_Presentation_and_Summ5

Basis of Presentation and Summary of Significant Accounting Policies - Summary of Customers Revenue Accounted for 10% or More of Total Revenue (Details) (Collaboration and License Revenue, Customer Concentration Risk)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Daiichi Sankyo - Related Party
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenues by single customer	74.00%	100.00%
Baxter
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenues by single customer	26.00%		92.00%

Basis_of_Presentation_and_Summ6

Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2014
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Estimated useful lives	3 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful lives	5 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Estimated useful lives	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated useful lives, description	Shorter of lease term or useful life

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012	Feb. 12, 2014
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities	$24,251
Convertible Preferred Stock Warranty Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities		0
Convertible Preferred Stock Warranty Liability | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities	24,251	0	1,738
Contingent Consideration | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities		6,495		1,310
Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets		148,012
Fair Value Measurements Recurring Basis | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets		148,012
Fair Value Measurements Recurring Basis | Convertible Preferred Stock Warranty Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities	24,251
Fair Value Measurements Recurring Basis | Convertible Preferred Stock Warranty Liability | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities	24,251
Fair Value Measurements Recurring Basis | Contingent Consideration
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities		6,495
Fair Value Measurements Recurring Basis | Contingent Consideration | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial liabilities		6,495
Fair Value Measurements Recurring Basis | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets		147,952
Fair Value Measurements Recurring Basis | Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets		147,952
Fair Value Measurements Recurring Basis | Restricted Cash (Money Market Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	50	60
Fair Value Measurements Recurring Basis | Restricted Cash (Money Market Funds) | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total financial assets	$50	$60

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Details) (USD $)	1 Months Ended	2 Months Ended	12 Months Ended			9 Months Ended
	Jul. 31, 2013	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Feb. 12, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other income (expense), net			($18,595,000)	($12,349,000)	$7,014,000
Reduction of debt				0
Convertible preferred stock warrant liability				24,251,000
Discount rate	30.00%	30.00%		30.00%
Reduction to conversion of cash payments outstanding principal percentage				100.00%
Series B Convertible Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Conversion of cash payments outstanding principal percentage				400.00%
Reduction to conversion of cash payments outstanding principal percentage				100.00%
Convertible Preferred Stock Warranty Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability			0
Convertible Preferred Stock Warranty Liability | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability			0	24,251,000	1,738,000
Contingent Consideration | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability			6,495,000				1,310,000
Warrant
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Embedded derivatives			4,100,000	4,100,000		4,100,000
Reduction of debt			0			0
Convertible Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Aggregate principal amount		10,000,000		10,000,000
Bridge Loan
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Initial fair value of the warrants				13,600,000		13,600,000
Other income (expense), net			3,600,000			3,600,000
Fair Value Measurements Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers of asset from Level 1 to Level 2			0	0
Transfers of liabilities from Level 1 to Level 2			0	0
Fair Value Measurements Recurring Basis | Convertible Preferred Stock Warranty Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability				24,251,000
Fair Value Measurements Recurring Basis | Convertible Preferred Stock Warranty Liability | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability				24,251,000
Fair Value Measurements Recurring Basis | Contingent Consideration
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability			6,495,000
Fair Value Measurements Recurring Basis | Contingent Consideration | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability			$6,495,000
Expected probability of earn-out payment occurrence			98.00%
Discount rate			25.00%
Counterparty credit risk given the cash payment			6.00%

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Convertible Preferred Stock Warrant Liability and Embedded Derivatives Based on Assumptions (Details)	1 Months Ended	2 Months Ended	12 Months Ended
	Jul. 31, 2013	Sep. 30, 2013	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Discount rate	30.00%	30.00%	30.00%
Weighted-average scenario probabilities:
New equity financing	25.00%	65.00%	63.00%
New equity financing at lower valuation then previous financing	5.00%	5.00%	7.00%
Initial public offering	5.00%	5.00%	10.00%
Change of control	25.00%	5.00%
Maturity	40.00%	20.00%	20.00%

Fair_Value_Measurements_Summar1

Fair Value Measurements - Summary of Changes in the Estimated Fair Value of Convertible Preferred Stock Warrants (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$24,251
Initial fair value of the warrants issued in excess of debt proceeds recognized in other income (expense), net		3,669
Remeasurement of convertible preferred stock warrant and embedded derivative liabilities	15,899	4,557	-639
Ending balance		24,251
Convertible Preferred Stock Warranty Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Ending balance	0
Convertible Preferred Stock Warranty Liability | Level 3
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	24,251	1,738
Warrants issued in connection with notes payable		9,950
Initial fair value of the warrants issued in excess of debt proceeds recognized in other income (expense), net		3,669
Warrants exercised	-40,150
Remeasurement of convertible preferred stock warrant and embedded derivative liabilities	15,899	8,894
Ending balance	$0	$24,251

Fair_Value_Measurements_Summar2

Fair Value Measurements - Summary of Changes in the Estimated Fair Value of Contingent Consideration (Details) (USD $)	11 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance		$24,251
Ending balance		24,251
Contingent Consideration | Level 3
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	1,310
Change in fair value of the contingent consideration liability	5,185
Ending balance	$6,495

Fair_Value_Measurements_Summar3

Fair Value Measurements - Summary of Changes in the Estimated Fair Value of Derivative Instrument (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Balance, beginning of year	$0
Initial fair value of the embedded derivative issued in excess of debt proceeds recognized in other income (expense), net	4,096
Change in fair value of embedded derivative	-4,096
Balance, end of year	$0

Balance_Sheet_Components_Sched

Balance Sheet Components - Schedule of Prepaid Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Prepaid Assets [Line Items]
Prepaid assets	$20,485	$5,688
Prepaid Clinical, Material, Manufacturing and Other - Related Parties
Schedule Of Prepaid Assets [Line Items]
Prepaid assets	5,990	3,177
Prepaid Clinical, Material and Manufacturing
Schedule Of Prepaid Assets [Line Items]
Prepaid assets	12,149	1,758
Prepaid Other
Schedule Of Prepaid Assets [Line Items]
Prepaid assets	$2,346	$753

Balance_Sheet_Components_Sched1

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property Plant And Equipment [Line Items]
Total property and equipment	$5,764	$2,368
Accumulated depreciation and amortization	-1,292	-625
Property and equipment, net	4,472	1,743
Machinery and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	4,317	2,051
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment	286	79
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	288	147
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	399	91
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$474

Balance_Sheet_Components_Addit

Balance Sheet Components - Additional Information (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property Plant And Equipment [Abstract]
Depreciation and amortization	$674	$404	$221

Balance_Sheet_Components_Sched2

Balance Sheet Components - Schedule of Accrued Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]
Accrued clinical, manufacturing and other - related parties	$2,997	$2,792
Accrued compensation	3,435	1,549
Accrued professional and consulting fees	252	995
Accrued other	4,547	1,922
Accrued liabilities	$11,231	$7,258

Collaboration_and_License_Agre2

Collaboration and License Agreements - Schedule of Revenue Related to Collaboration and License Agreements (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total collaboration and license revenue	$30,374	$2,751	$1,899
Baxter
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total collaboration and license revenue	28,481	726
Daiichi Sankyo - Related Party
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total collaboration and license revenue	$1,893	$2,025	$1,899

Collaboration_and_License_Agre3

Collaboration and License Agreements - Additional Information (Details) (USD $)	12 Months Ended			1 Months Ended		3 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2014	Aug. 31, 2013	Sep. 30, 2014	Jun. 30, 2013	Jan. 31, 2012
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Convertible preferred stock, shares issued		9,153,906
Proceeds from issuance of convertible preferred stock, net of issuance costs	$54,660,000		$26,938,000
Convertible preferred stock		54,695,000
Deferred revenue, current	22,800,000	14,283,000
Deferred revenue, non-current	39,899,000	28,567,000
Collaboration and license revenue	30,374,000	2,751,000	1,899,000
Contingent liability to collaborator	27,650,000	7,500,000
Baxter License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	58,400,000	36,800,000
Initial term of agreement					10 years
Renewal term of agreement					3 years
Estimated period of performance upfront fee					3 years
Deferred revenue, current	21,200,000	12,300,000
Deferred revenue, non-current	37,200,000	24,500,000
Collaboration and license revenue	28,481,000	726,000			30,000,000	10,000,000
Contingent payment receivable					120,000,000
Prior written notice of termination of license agreement					18 months
Contingent payment development related expenses				71,300,000	56,000,000
Contingent payments refundable, percentage					50.00%
Expiration or termination of license agreement					10 years
Increase in license agreement non-substantive contingent milestone receivable				5,300,000
Contingent liability to collaborator	27,700,000	7,500,000
Baxter License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payment receivable				221,300,000	216,000,000
Baxter License Agreement | Maximum | Clinical Development Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payment receivable				101,300,000	96,000,000
Baxter License Agreement | Maximum | Regulatory Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payment receivable				120,000,000	120,000,000
Daiichi Sankyo - Related Party
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	4,300,000	6,100,000						10,000,000
Initial term of agreement								10 years
Renewal term of agreement								3 years
Estimated period of performance upfront fee	3 years
License agreement finalized period							90 days
Percentage of budgeted cost, total							33.00%
Percentage of cost of comparator drug							100.00%
Minimum percentage of clinical trial cost								20.00%
Advance payments	1,200,000
Deferred revenue, current	1,600,000	2,000,000
Deferred revenue, non-current	2,700,000	4,100,000
Research and development	7,100,000	1,300,000	158,000
Collaboration and license revenue	1,893,000	2,025,000	1,899,000
Series B Convertible Preferred Stock | Daiichi Sankyo - Related Party
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Convertible preferred stock, shares issued								2,867,426
Convertible preferred stock, par value								$6.97
Proceeds from issuance of convertible preferred stock, net of issuance costs								18,100,000
Convertible Preferred Stock | Daiichi Sankyo - Related Party
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Convertible preferred stock								$18,100,000

Acquisition_of_InteKrin_Therap2

Acquisition of InteKrin Therapeutics, Inc. - Additional Information (Details)

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Feb. 12, 2014

Feb. 12, 2014

Dec. 31, 2014

Jan. 08, 2014

Dec. 31, 2014

Dec. 31, 2014

Mar. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Jan. 08, 2014

Dec. 31, 2014

Jan. 08, 2014

Dec. 31, 2014

Jan. 08, 2014

Dec. 31, 2014

Jan. 08, 2014

USD ($)

Maximum

Minimum

Contingent Consideration Earn-out Payment

Contingent Consideration Compound Transaction Payment

Series B Convertible Preferred Stock

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

Coherus Intermediate Corp, InteKrin Therapeutics, Inc.

Coherus Intermediate Corp, InteKrin Therapeutics, Inc.

Agreement

Year One

Year Three

USD ($)

USD ($)

USD ($)

USD ($)

RUB

RUB

Two Thousand Fourteen

Two Thousand Fifteen

In Process Research and Development

Series B Convertible Preferred Stock

Series B Convertible Preferred Stock

Series B Convertible Preferred Stock

General and Administrative Expense

PWERM

RUSSIA

RUSSIA

RUB

RUB

USD ($)

USD ($)

USD ($)

USD ($)

Series B Convertible Preferred Stock

InteKrin Therapeutics Inc

InteKrin Therapeutics Inc

USD ($)

Business Acquisition [Line Items]

Business acquisition, date of acquisition agreement

8-Jan-14

Business acquisition, description of acquired entity

All of the outstanding shares of InteKrin and its 82.5% majority owned subsidiary, InteKrin Russia

All of the outstanding shares of InteKrin and its 82.5% majority owned subsidiary, InteKrin Russia

Controlling interest, ownership percentage by parent

82.50%

82.50%

Business acquisition, effective date of acquisition

12-Feb-14

Business Combination Consideration Transferred1

$5,000,000

Business combination, reason for business combination

Additionally, the acquisition of InteKrin was a strategic transaction to obtain funding from new investors.

Additionally, the acquisition of InteKrin was a strategic transaction to obtain funding from new investors.

Business acquisition costs, legal expenses

134,000

Business acquisition, number of shares issued

358,384

716,645

243,841

Business acquisition, value of shares issued

2,700,000

1,000,000

Business acquisition, cash payment

1,485

Business acquisition, contingent consideration

6,500,000

1,300,000

Convertible preferred stock, par value

$3.82

Business acquisition, fair value method

PWERM

Estimated acquisition represents fair value

2,600,000

Impairment of intangible assets excluding goodwill

0

Number of contingent consideration for potential payments

2

Contingent consideration, probability of completion

75.00%

Fair value of contingent consideration

800,000

500,000

Percent of administrative fees received

60.00%

10.00%

Fair value inputs contingent probability

7.50%

Remeasurement of contingent consideration

5,185,000

Impairment of goodwill

0

Research and development expense

2,600,000

147,900,000

40,000,000

39,400,000

Deferred revenue

28,000,000

12,000,000

Deferred revenue, recognized

$732,000

40,000,000

0

Acquisition_of_InteKrin_Therap3

Acquisition of InteKrin Therapeutics, Inc. - Fair Value of Assets Acquired and Liabilities Assumed (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Business Combination Recognized Identifiable Assets Acquired Goodwill And Liabilities Assumed Net [Abstract]
Cash	$2,335
Prepaid and other assets	107
Accounts payable and other current liabilities	-1,027
In-process research and development	2,620
Goodwill	943
Total consideration	$4,978

Debt_Obligations_Additional_In

Debt Obligations - Additional Information (Details) (USD $)	9 Months Ended	12 Months Ended			1 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2012	31-May-14	Jul. 31, 2011	Sep. 30, 2013	Dec. 09, 2013	Dec. 31, 2011	Sep. 30, 2011
Debt Instrument [Line Items]
Accrued employee compensation and/or bonuses payable converted to convertible notes				$10,631,000
Beneficial conversion feature amount		-3,939,000		-10,631,000
Gains on extinguishment of debt		2,048,000		6,369,000
Total interest expense related to accrued interest and amortization of debt discount		3,900,000	4,800,000
Beneficial conversion feature	0
Interest on outstanding debt		3,900,000	5,293,000	1,514,000
Other income (expense), net		-18,595,000	-12,349,000	7,014,000
Reduction of debt			0
Reduction to conversion of cash payments outstanding principal percentage			100.00%
Reduction to accrued interest and derivative liability			0
Warrant
Debt Instrument [Line Items]
Fair value of embedded derivative liability	4,100,000	4,100,000	4,100,000
Reduction of debt	0	0
Minimum
Debt Instrument [Line Items]
Accounts receivable related parties current								50,000,000
Proceeds from execution of Agreement								25,000,000
Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Outstanding principal amount					10,400,000
Accrued interest of notes					236,000
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares					1,524,134
Convertible preferred stock conversion price					$6.97			$6.97
Stock issued for warrant exercised					352,448				4,279,620
Conversion of cash payments outstanding principal percentage			400.00%
Reduction to conversion of cash payments outstanding principal percentage			100.00%
Convertible Preferred Stock
Debt Instrument [Line Items]
Warrant exercise price	$0.02
Series C Convertible Preferred Stock
Debt Instrument [Line Items]
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares		1,058,089				1,058,089
IPO | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Convertible preferred stock conversion price								$6.97
2011 Notes
Debt Instrument [Line Items]
Aggregate principal amount							3,800,000			6,600,000	10,400,000
Cash received from investors							3,500,000
Accrued employee compensation and/or bonuses payable converted to convertible notes							260,000
Accrued interest										8.00%
Debt instrument maturity date		31-Mar-12
Term of debt instrument		The outstanding principal and accrued interest on the 2011 Notes were convertible: (i) automatically upon a financing event in which the Company issued newly authorized shares of stock into that same stock at a conversion price equal to the price paid by the other investors in that financing event, (ii) upon a change of control or IPO, at the option of the note holder, into shares of Series A convertible preferred stock at a conversion price of $1.2503 per share or (iii) upon the maturity date, at the request of the majority note holders, if the financing event above had not occurred on or before the maturity date, into shares of Series A convertible preferred stock at a conversion price of $1.2503 per share. In connection with the issuance of the 2011 Notes, the Company issued warrants (the b2011 Warrants Bb) to purchase shares of its preferred stock at an exercise price of $0.0167 per share
Warrant exercise price										$0.02	$0.02
Initial fair value of the warrants		2,700,000
Beneficial conversion feature amount		5,400,000
Gains on extinguishment of debt					6,400,000
Total interest expense related to accrued interest and amortization of debt discount				1,500,000
Beneficial conversion feature				1,000,000
Debt discount amortization				433,000
Interest on outstanding debt				53,000
2011 Notes | IPO | Series A Preferred Stock
Debt Instrument [Line Items]
Convertible preferred stock conversion price										$1.25
Convertible Debt
Debt Instrument [Line Items]
Aggregate principal amount			10,000,000					10,000,000
Accrued interest								8.00%
Debt instrument maturity date		15-Jul-14
Bridge Loan
Debt Instrument [Line Items]
Warrant exercise price								$0.02
Initial fair value of the warrants	13,600,000		13,600,000
Gains on extinguishment of debt						2,000,000
Percentage on shares issuable to warrants	300.00%
Other income (expense), net	3,600,000	3,600,000
Debt instrument, unamortized discount	10,000,000
Bridge loans and related accrued interest						10,600,000
Intrinsic value on loans extinguishment						3,900,000

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Purchase Commitment Excluding Longterm Commitment [Line Items]
Rent expense	$763,000	$428,000	$371,000
Payment of claims	0
Corporate Headquarters Lease
Purchase Commitment Excluding Longterm Commitment [Line Items]
Lease expiration date	30-Apr-17
Leases extended expiration period	3 years
Laboratory Lease
Purchase Commitment Excluding Longterm Commitment [Line Items]
Lease expiration date	30-Jun-17
Leases extended expiration period	3 years
CMOs
Purchase Commitment Excluding Longterm Commitment [Line Items]
Contractual commitment	4,800,000
Medpace Inc
Purchase Commitment Excluding Longterm Commitment [Line Items]
Minimum fee commitment	35,000,000
Purchase commitment amount of services performed	$20,700,000
Period of contract termination	30 days

Commitments_and_Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Lease Payments for Facilities (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Leases Future Minimum Payments Due [Abstract]
2015	$1,082
2016	1,117
2017	404
Total minimum lease payments	$2,603

Convertible_Preferred_Stock_Wa2

Convertible Preferred Stock Warrants - Convertible Preferred Stock Warrants and Related Estimated Fair Values (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013
Class Of Warrant Or Right [Line Items]
Shares Underlying the Warrants	4,638,644
Convertible preferred stock warrant liability	$24,251
2013 Warrants
Class Of Warrant Or Right [Line Items]
Shares Underlying the Warrants	4,279,620
Convertible preferred stock warrant liability	22,959
Series A Convertible Preferred Stock | 2011 Warrants A
Class Of Warrant Or Right [Line Items]
Shares Underlying the Warrants	63,923
Convertible preferred stock warrant liability	170
Series B Convertible Preferred Stock | 2011 Warrants B
Class Of Warrant Or Right [Line Items]
Shares Underlying the Warrants	295,101
Convertible preferred stock warrant liability	$1,122

Convertible_Preferred_Stock_Wa3

Convertible Preferred Stock Warrants - Additional Information (Details) (USD $)	1 Months Ended	2 Months Ended	12 Months Ended			9 Months Ended	6 Months Ended	1 Months Ended						2 Months Ended	3 Months Ended
	Jul. 31, 2013	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Dec. 31, 2011	31-May-14	Apr. 30, 2014	Dec. 31, 2012	Jun. 30, 2012	Jan. 31, 2012	Nov. 30, 2014	31-May-14	Sep. 30, 2013	Mar. 31, 2011	Dec. 09, 2013
Class Of Stock [Line Items]
Proceeds from issuance of convertible preferred stock upon exercise of warrants			$131,000
Proceeds from issuance of convertible preferred stock, net of issuance costs			54,660,000		26,938,000
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise			40,150,000		400,000
Discount rate	30.00%	30.00%		30.00%
Other income (expense), net			-18,595,000	-12,349,000	7,014,000
Change in fair value of Warrant liability			15,900,000	8,900,000	-600,000
Bridge Loan
Class Of Stock [Line Items]
Warrant exercise price		0.0167													$0.02
Initial fair value of the warrants				13,600,000		13,600,000
Percentage on shares issuable to warrants						300.00%
Other income (expense), net			3,600,000			3,600,000
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Stock issued for warrant exercised													62,251
Principal loan amount of initial closing, percentage							30.00%
Principal loan amount of subsequent closing, percentage							20.00%
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise			1,000,000
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Stock issued for warrant exercised								4,451,662	4,451,662		57,347		123,051	4,451,662
Proceeds from issuance of convertible preferred stock upon exercise of warrants								74,000	74,000
Proceeds from issuance of convertible preferred stock, net of issuance costs										6,600,000	1,000	20,300,000
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise			39,300,000								400,000
Convertible preferred stock conversion price					$6.97					$6.97		$6.97
Series B Convertible Preferred Stock | Bridge Loan
Class Of Stock [Line Items]
Stock issued for warrant exercised								4,279,620	4,279,620					4,279,620
2011 Warrants A
Class Of Stock [Line Items]
Expiration date of warrants			25-Jan-16
Initial fair value of the warrants																53,000
2011 Warrants A | Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Stock issued for warrant exercised													62,251			63,923
Convertible preferred stock conversion price																$1.25
Proceeds from issuance of convertible preferred stock upon exercise of warrants													55,000
2011 Warrants B
Class Of Stock [Line Items]
Warrant exercise price							0.0167
Warrants exercisable Period							7 years
Principal loan amount of initial closing, percentage							30.00%
Principal loan amount of subsequent closing, percentage							20.00%
Initial fair value of the warrants			2,700,000
2011 Warrants B | Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Stock issued for warrant exercised								172,042				352,448	123,051	172,042
Proceeds from issuance of convertible preferred stock upon exercise of warrants													2,000	3,000
2013 Warrants | Bridge Loan
Class Of Stock [Line Items]
Warrant exercise price		0.0167													$0.02
Warrants exercisable Period															7 years
Initial fair value of the warrants																	13,600,000
Percentage on shares issuable to warrants			300.00%
Discount rate			30.00%
Aggregate principal amount																	10,000,000
Other income (expense), net			3,600,000
2013 Warrants | Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock conversion price		6.9749													$6.97
2013 Warrants | Series B Convertible Preferred Stock | Bridge Loan
Class Of Stock [Line Items]
Stock issued for warrant exercised								4,279,620						4,279,620			4,279,620
Proceeds from issuance of convertible preferred stock upon exercise of warrants														$71,000

Convertible_Preferred_Stock_Wa4

Convertible Preferred Stock Warrants - Summary of Estimated Fair Value of Warrants Issuance Based on Probability Weighted Present Values with Qualifying Event Scenarios (Details) (2011 Warrants B)	12 Months Ended
	Dec. 31, 2014
Issuance Date One
Temporary Equity [Line Items]
Issuance Date	21-Jul-11
Issuance Date One | Scenario One
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	35.00%
Issuance Date One | Scenario Two
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	65.00%
Issuance Date Two
Temporary Equity [Line Items]
Issuance Date	31-Aug-11
Issuance Date Two | Scenario One
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	50.00%
Issuance Date Two | Scenario Two
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	50.00%
Issuance Date Three
Temporary Equity [Line Items]
Issuance Date	31-Oct-11
Issuance Date Three | Scenario One
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	75.00%
Issuance Date Three | Scenario Two
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	25.00%
Issuance Date Four
Temporary Equity [Line Items]
Issuance Date	29-Nov-11
Issuance Date Four | Scenario One
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	85.00%
Issuance Date Four | Scenario Two
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	15.00%
Issuance Date Five
Temporary Equity [Line Items]
Issuance Date	21-Dec-11
Issuance Date Five | Scenario One
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	90.00%
Issuance Date Five | Scenario Two
Temporary Equity [Line Items]
Percentage of preferred stock issued newly authorized	10.00%

Common_Stock_Warrants_Addition

Common Stock Warrants - Additional Information (Details) (USD $)	12 Months Ended			1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Nov. 12, 2014
Class Of Warrant Or Right [Line Items]
Common stock, per share value				$5.73
Stock-based compensation expense	$11,062	$2,045	$443
Employee Warrants
Class Of Warrant Or Right [Line Items]
Common stock, per share value				$4.95
Consultant Warrants
Class Of Warrant Or Right [Line Items]
Common stock, per share value				$5.42
Common Stock
Class Of Warrant Or Right [Line Items]
Issued warrants to purchase shares of common stock				553,274
Common stock, exercise price				$1.67
Initial fair value of the warrants				2,700
Common Stock | IPO
Class Of Warrant Or Right [Line Items]
Issued warrants to purchase shares of common stock					491,580
Common Stock | Employee Warrants
Class Of Warrant Or Right [Line Items]
Initial fair value of the warrants				2,600
Common Stock | Consultant Warrants
Class Of Warrant Or Right [Line Items]
Initial fair value of the warrants				144
Warrant
Class Of Warrant Or Right [Line Items]
Dividend yield				0.00%
Fair value assumptions, exercise price				$1.67
Warrant | Research and Development Expense
Class Of Warrant Or Right [Line Items]
Stock-based compensation expense				1,300
Warrant | General and Administrative Expense
Class Of Warrant Or Right [Line Items]
Stock-based compensation expense				$1,400
Warrant | Employee Warrants
Class Of Warrant Or Right [Line Items]
Expected volatility				93.00%
Risk-free interest rate				1.74%
Expected terms				5 years
Warrant | Consultant Warrants
Class Of Warrant Or Right [Line Items]
Expected volatility				96.00%
Risk-free interest rate				2.73%
Expected terms				10 years

Convertible_Preferred_Stock_an2

Convertible Preferred Stock and Stockholders Equity (Deficit) - Additional Information (Details) (USD $)	0 Months Ended	12 Months Ended		1 Months Ended
	Nov. 12, 2014	Dec. 31, 2014	Dec. 31, 2012	31-May-14	Apr. 30, 2014	Dec. 31, 2012	Jun. 30, 2012	Jan. 31, 2012	Nov. 30, 2014	Dec. 31, 2013	Dec. 31, 2011
Class Of Stock [Line Items]
Common stock, shares authorized		300,000,000
Common stock, par value		$0.00								$0.00
Preferred stock, shares authorized		5,000,000
Preferred stock, par value		$0.00								$0.00
Convertible preferred stock, shares issued										9,153,906
Proceeds from issuance of convertible preferred stock, net of issuance costs		$54,660,000	$26,938,000
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise		40,150,000	400,000
Issuance of common stock options in exchange for services		48,000
Convertible preferred stock										54,695,000
Preferred stock, shares issued		0								0
Proceeds from issuance of convertible preferred stock upon exercise of warrants		131,000
Common stock issued upon, conversion of convertible preferred stock	21,316,519
Stock conversion ratio	1
Convertible preferred stock, shares outstanding		0								9,153,906
Bridge Loan
Class Of Stock [Line Items]
Bridge loans and related accrued interest				10,600,000
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares issued		0	1,146,970			1,146,970		3,225,854		8,181,576
Convertible preferred stock conversion price			$6.97			$6.97		$6.97
Proceeds from issuance of convertible preferred stock, net of issuance costs						6,600,000	1,000	20,300,000
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares			1,524,134					1,524,134
Stock issued for warrant exercised				4,451,662	4,451,662		57,347		123,051
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise		39,300,000					400,000
Preferred stock issued in exchange for services						1,725,472		501,799
Issuance of common stock options in exchange for services						12,000,000		3,500,000
Convertible preferred stock										53,504,000
Proceeds from issuance of convertible preferred stock upon exercise of warrants				74,000	74,000
Convertible preferred stock, shares outstanding		0	8,181,576			8,181,576				8,181,576
Series B Convertible Preferred Stock | Cook
Class Of Stock [Line Items]
Convertible preferred stock, shares issued			716,856			716,856
Convertible preferred stock			5,000,000			5,000,000
Series B Convertible Preferred Stock | 2011 Notes
Class Of Stock [Line Items]
Bridge loans and related accrued interest								10,600,000
Series B Convertible Preferred Stock | Bridge Loan
Class Of Stock [Line Items]
Stock issued for warrant exercised				4,279,620	4,279,620
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Proceeds from issuance of convertible preferred stock, net of issuance costs				54,700,000
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares		1,058,089		1,058,089
Preferred stock issued in exchange for services				9,997
Preferred stock, shares issued				5,488,892
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares issued		0								972,330
Stock issued for warrant exercised									62,251
Reclassification of fair value of convertible preferred stock warrants to preferred stock upon exercise		1,000,000
Convertible preferred stock										1,191,000
Convertible preferred stock, shares outstanding		0	972,330			972,330				972,330	972,330
Series A and Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Proceeds from issuance of convertible preferred stock upon exercise of warrants									57,000
Series A, Series B and Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Stock conversion ratio		1
Dividends declared		$0
Amended and Restated Certificate of Incorporation
Class Of Stock [Line Items]
Common stock, shares authorized	300,000,000
Common stock, par value	0.0001
Preferred stock, shares authorized	5,000,000
Preferred stock, par value	0.0001

Convertible_Preferred_Stock_an3

Convertible Preferred Stock and Stockholders Equity (Deficit) - Schedule of Outstanding Convertible Preferred Stock (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2012
In Thousands, except Share data, unless otherwise specified
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		28,090,997
Convertible preferred stock, shares issued		9,153,906
Convertible preferred stock, shares outstanding	0	9,153,906
Convertible preferred stock, carrying value		$54,695
Convertible preferred stock, liquidation preference		58,282
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	0	1,800,000
Convertible preferred stock, shares issued	0	972,330
Convertible preferred stock, shares outstanding	0	972,330	972,330	972,330
Convertible preferred stock, carrying value		1,191
Convertible preferred stock, liquidation preference		1,216
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	0	26,290,997
Convertible preferred stock, shares issued	0	8,181,576	1,146,970		3,225,854
Convertible preferred stock, shares outstanding	0	8,181,576	8,181,576
Convertible preferred stock, carrying value		53,504
Convertible preferred stock, liquidation preference		$57,066

Stock_Option_Plans_and_StockBa2

Stock Option Plans and Stock-Based Compensation - Additional Information (Details) (USD $)	12 Months Ended			1 Months Ended					12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 31, 2014	Mar. 31, 2014	Jul. 31, 2012	Jan. 31, 2011	Oct. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 10, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued	33,257,978	4,837,715
Common stock, par value	$0.00	$0.00
Options outstanding	5,770,307	3,047,396	1,535,095						974,797		5,770,307
Expected dividend yield	$0
Share based payment options vested	4,200,000	700,000	95,000
Share based payment options grants, grant-date fair value	$6.65	$1.88	$1.73
Share based payment options exercises value	391,000	0	46,000
Unrecognized stock-based compensation expenses related to stock options	18,500,000
Unrecognized share-based compensation related to stock options, period for recognition	3 years 3 months 11 days
Share based payment options grants	614,062	853,244	611,285
Weighted-Average Exercise Price, Granted - at fair value	$13.91	$2.08	$2.08
2010 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares of common stock subject to repurchase	0	0
Vesting period	4 years
Options granted, expiration period	10 years
Options outstanding	5,560,345
2014 Equity Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares available for issuance	4.00%
Common stock reserved for future issuance				2,300,000
2014 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance				320,000
2014 Employee Stock Purchase Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares reserve for issuance				1.00%
Restricted Common Stock (Founders Shares)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued							968,804	4,130,173
Common stock, par value							$0.01	$0.01
Repurchase of common stock, monthly equal installments period							4 years	4 years
Common stock shares repurchased			286,817		239,952	286,817
Common stock repurchased, cost per share					$0.01	$0.01
Unvested shares of common stock subject to repurchase	21,245	763,329
Vesting period	4 years
Estimated weighted-average grant date fair value									$0.41	$0.41
Common stock granted	0	0
Unrecognized stock compensation expense	9,000
Unrecognized stock compensation expense, vest over remaining service period	3 months 18 days
Stock-based compensation expense	1,551,000	1,281,000	342,000
Restricted Common Stock (Founders Shares) | General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	4,000	1,054,000	110,000
Restricted Common Stock (Founders Shares) | Accrued and Other Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares of common stock subject to repurchase amount	200	5,000
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	5,514,000	740,000	95,000
Employee Stock Option | General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	3,934,000	309,000	65,000
Employee Stock Option | Former CFO | General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,200,000
Nonemployees Stock-Based Compensation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$1,300,000	$24,000	$6,000
Share based payment options grants	113,913	74,983
Weighted-Average Exercise Price, Granted - at fair value	$4.42	$1.42

Stock_Option_Plans_and_StockBa3

Stock Option Plans and Stock-Based Compensation - Summary of Non-Vested Restricted Stock (Details) (Restricted Common Stock (Founders Shares))	1 Months Ended		12 Months Ended
	Mar. 31, 2014	Jul. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Common Stock (Founders Shares)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Non-vested, beginning balance			763,329	2,150,979	3,644,858
Number of Shares, Vested			-742,084	-1,387,650	-1,207,062
Number of Shares, Repurchased by the Company	-239,952	-286,817			-286,817
Number of Shares, Non-vested, ending balance			21,245	763,329	2,150,979

Stock_Option_Plans_and_StockBa4

Stock Option Plans and Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Related to Founder's Shares (Details) (Restricted Common Stock (Founders Shares), USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$1,551	$1,281	$342
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,547	227	232
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$4	$1,054	$110

Stock_Option_Plans_and_StockBa5

Stock Option Plans and Stock-Based Compensation - Summary of Option Activities under 2014 and 2010 Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 10, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Beginning balance	1,024,245	953,224	14,999
Shares Available for Grant, Authorized	4,399,580	1,586,570	1,520,830
Shares Available for Grant, Granted - at fair value	-614,062	-853,244	-611,285
Shares Available for Grant, Granted - below fair value	-2,703,441	-786,018
Shares Available for Grant, Forfeited	546,178	123,713	28,680
Shares Available for Grant, Ending balance	2,652,500	1,024,245	953,224
Number of Options, Beginning balance	3,047,396	1,535,095	974,797	5,770,307
Number of Options, Granted - at fair value	614,062	853,244	611,285
Number of Options, Granted - below fair value	2,703,441	786,018
Number of Options, Exercised	-48,414	-3,248	-22,307
Number of Options, Forfeited	-546,178	-123,713	-28,680
Number of Options, Ending balance	5,770,307	3,047,396	1,535,095	5,770,307
Weighted-Average Exercise Price, Beginning balance	$1.43	$1.06	$0.36
Weighted-Average Exercise Price, Granted - at fair value	$13.91	$2.08	$2.08
Weighted-Average Exercise Price, Granted - below fair value	$1.83	$1.42
Weighted-Average Exercise Price, Exercised	$1.14	$2.08	$0.01
Weighted-Average Exercise Price, Forfeited	$1.83	$1.27	$0.01
Weighted-Average Exercise Price, Ending balance	$2.91	$1.43	$1.06

Stock_Option_Plans_and_StockBa6

Stock Option Plans and Stock-Based Compensation - Summary of Additional Information Related to Status of Options (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 10, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, Number of Options	5,770,307	5,770,307	3,047,396	1,535,095	974,797
Options vested and expected to vest, Number of Options	5,764,337
Options vested, Number of Options	2,364,401
Options exercisable, Number of Options	2,365,651
Options outstanding, Weighted-Average Exercise Price	$2.91		$1.43	$1.06	$0.36
Options vested and expected to vest, Weighted-Average Exercise Price	$2.91
Options vested, Weighted-Average Exercise Price	$1.48
Option exercisable, Weighted-Average Exercise Price	$1.48
Options outstanding, Weighted-Average Contractual Terms	8 years 7 months 24 days
Options vested and expected to vest, Weighted-Average Contractual Terms	8 years 7 months 21 days
Options vested, Weighted-Average Contractual Terms	8 years 5 months 27 days
Options exercisable, Weighted-Average Contractual Terms	7 years 10 months 24 days
Options outstanding, Aggregate Intrinsic Value	$77,383
Options vested and expected to vest, Aggregate Intrinsic Value	77,303
Options vested, Aggregate Intrinsic Value	35,080
Options exercisable, Aggregate Intrinsic Value	$35,101

Stock_Option_Plans_and_StockBa7

Stock Option Plans and Stock-Based Compensation - Schedule of Weighted Average Assumptions Used to Value Options Granted to Employees (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (years)	6 years 6 months	5 years 6 months 4 days	6 years 15 days
Expected volatility	99.00%	108.00%	110.00%
Risk-free interest rate	2.05%	1.23%	0.93%
Expected dividend yield	0.00%	0.00%	0.00%

Stock_Option_Plans_and_StockBa8

Stock Option Plans and Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Related to Options (Details) (Employee Stock Option, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$5,514	$740	$95
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,580	431	30
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$3,934	$309	$65

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Statutory U.S. Federal Rate (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Percent of pre-tax income:
U.S. federal statutory income tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	-1.65%	3.97%	6.68%
Permanent items	-10.80%	-12.40%	5.65%
Research and development credit	3.11%	4.53%
Net operating loss	0.01%
InteKrin purchase price allocation	0.73%
Other	0.02%		-0.17%
Change in valuation allowance	-25.42%	-30.10%	-46.16%
Effective income tax rate	0.00%	0.00%	0.00%

Income_Taxes_Components_of_Net

Income Taxes - Components of Net Deferred Tax Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Components Of Deferred Tax Assets [Abstract]
Net operating loss carryforwards	$34,463	$27,524
Research and development credits	6,032	2,823
Depreciation and amortization	854	26
Stock-based compensation	1,428	82
Other accruals	940	626
Deferred revenue	12,762	2,413
Gross deferred tax assets	56,479	33,494
In-process research and development	-892
Gross deferred tax liabilities	-892
Total net deferred tax asset	55,587	33,494
Less valuation allowance	-55,587	-33,494
Net deferred tax assets	$0	$0

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Increase in valuation allowance	$22,100,000	$16,100,000
Tax effect of stock option benefit that will be recorded to equity	1,600,000
Unrecognized tax benefits, accrued interest and penalties accrued	0	0	0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	97,300,000
Net operating loss carryforwards expiration year	2031
Tax credit carryforwards	6,500,000
Tax credit carryforwards expiration year	2031
Federal | Stock Options
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	4,700,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	64,500,000
Net operating loss carryforwards expiration year	2031
Tax credit carryforwards	$1,600,000

Income_Taxes_Reconciliation_of1

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Balance at beginning of year	$749	$73	$14
Additions based on tax positions related to current year	861	319	59
Additions for tax positions of prior years	2,206	357
Balance at end of year	$3,816	$749	$73

Net_Loss_Per_Share_Attributabl2

Net Loss Per Share Attributable to Coherus - Computation of Basic and Diluted Net Loss Per Share Attributable to Coherus (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator:
Net loss attributable to Coherus	($29,134)	($7,872)	($24,957)	($25,170)	($14,591)	($21,473)	($8,709)	($8,862)	($87,133)	($53,635)	($33,018)
Denominator:
Weighted-average common shares outstanding									8,520,100	4,828,214	4,963,883
Less: weighted-average unvested common shares subject to repurchase									-333,571	-1,496,194	-2,881,261
Weighted-average number of shares used in computing net loss per share attributable to Coherus, basic and diluted									8,186,529	3,332,020	2,082,622
Net loss per share attributable to Coherus, basic and diluted	($1.47)	($1.79)	($5.96)	($6.04)	($3.68)	($6.23)	($2.80)	($3.14)	($10.64)	($16.10)	($15.85)

Net_Loss_Per_Share_Attributabl3

Net Loss Per Share Attributable to Coherus - Outstanding Dilutive Potential Shares Excluded from Calculation of Diluted Net Loss Per Share Attributable to Coherus (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share	5,770,307	16,839,946	11,048,025
Stock Options Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share	5,770,307	3,047,396	1,535,095
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share		9,153,906	9,153,906
Convertible Preferred Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share		4,638,644	359,024

Net_Loss_Per_Share_Attributabl4

Net Loss Per Share Attributable to Coherus - Additional Information (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share	5,770,307	16,839,946	11,048,025
Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from the calculation of diluted net loss per share	358,384

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Details) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	31-May-14	Jan. 31, 2012	Feb. 28, 2014	Sep. 30, 2011	Jul. 31, 2011	Sep. 30, 2013	Dec. 09, 2013	Nov. 30, 2014
				Founders
Related Party Transaction [Line Items]
Notes receivable from related parties		$107,000		133,000
Convertible preferred stock, shares issued		9,153,906
Collaboration and license revenue	30,374,000	2,751,000	1,899,000
Deferred revenue	22,800,000	14,283,000
Deferred revenue, non-current	39,899,000	28,567,000
Prepaid assets	20,485,000	5,688,000
Research and development expense	78,224,000	31,279,000	34,886,000
Accounts payable - related parties	2,020,000	383,000
Accrued liabilities	11,231,000	7,258,000
Interest expense from transactions with related party	2,687,000	4,026,000	1,059,000
General and administrative expenses from transactions with related party	597,000	18,000	61,000
Other assets - related party	1,691,000
2011 Notes
Related Party Transaction [Line Items]
Aggregate principal amount				6,600,000				10,400,000	3,800,000
Warrant exercise price				0.0167				$0.02
Total aggregate amount from related parties								9,300,000
Bridge Loan
Related Party Transaction [Line Items]
Interest expense from transactions with related party	2,700,000	3,300,000	1,100,000
Warrant exercise price										$0.02
Total aggregate amount from related parties										7,100,000
Series B Convertible Preferred Stock
Related Party Transaction [Line Items]
Convertible preferred stock conversion price						$6.97				$6.97
Stock issued for warrant exercised						352,448					4,279,620
Prepaid Clinical, Material, Manufacturing and Other - Related Parties
Related Party Transaction [Line Items]
Prepaid assets	5,990,000	3,177,000
Executive Officer
Related Party Transaction [Line Items]
Number of founders entered into notes receivable agreement				3
Daiichi Sankyo - Related Party
Related Party Transaction [Line Items]
Collaboration and license revenue	1,893,000	2,025,000	1,899,000
Deferred revenue under collaboration license agreement	4,300,000	6,100,000				10,000,000
Deferred revenue	1,600,000	2,000,000
Deferred revenue, non-current	2,700,000	4,100,000
Reduction of research and development expense	7,100,000	1,300,000	158,000
Daiichi Sankyo - Related Party | Series B Convertible Preferred Stock
Related Party Transaction [Line Items]
Convertible preferred stock, shares issued						2,867,426
Daiichi Sankyo - Related Party | Series B
Related Party Transaction [Line Items]
Convertible preferred stock, shares issued						2,867,426
Daiichi Sankyo - Related Party | Minimum
Related Party Transaction [Line Items]
Related party transaction ownership percentage						10.00%
Daiichi Sankyo - Related Party | Maximum
Related Party Transaction [Line Items]
Related party transaction ownership percentage												10.00%
Cook
Related Party Transaction [Line Items]
Receivables from related parties		278,000
Research and development expense	4,500,000	6,100,000	15,800,000
Cook | Prepaid Clinical, Material, Manufacturing and Other - Related Parties
Related Party Transaction [Line Items]
Prepaid assets		3,000,000
Cook | Series B
Related Party Transaction [Line Items]
Convertible preferred stock, shares issued			2,150,569			2,150,569
Cook | Minimum | Series B
Related Party Transaction [Line Items]
Related party transaction ownership percentage			10.00%			10.00%
Medpace Inc
Related Party Transaction [Line Items]
Research and development expense	24,100,000	4,700,000	1,000,000
Accounts payable - related parties	1,900,000	383,000
Interest expense from transactions with related party		500,000
Minimum fee commitment	35,000,000
Purchase commitment amount of services performed	20,700,000
Medpace Inc | Prepaid Clinical, Material, Manufacturing and Other - Related Parties
Related Party Transaction [Line Items]
Prepaid assets	6,000,000	198,000
Medpace Inc | Accrued Clinical, Manufacturing and Other - Related Parties
Related Party Transaction [Line Items]
Accrued liabilities	2,997,000	2,792,000
Recruiting Services
Related Party Transaction [Line Items]
Research and development expense	241,000	35,000	163,000
Accounts payable - related parties	90,000	0
General and administrative expenses from transactions with related party	597,000	18,000	61,000
Founders
Related Party Transaction [Line Items]
Number of founders entered into notes receivable agreement				4
Note receivable interest rate				0.20%
Imputed interest rate in relation to the notes				4.00%
Outstanding balance of notes receivable					111,000
Accrued interest amount forgiven	1,000
Related Parties | Bridge Loan
Related Party Transaction [Line Items]
Aggregate principal amount										10,000,000
Carrying value of the bridge loans net of discount		3,100,000
Related Parties | Series B Convertible Preferred Stock | 2011 Notes
Related Party Transaction [Line Items]
Accrued interest of notes						193,000
Issuance of convertible preferred stock shares upon conversion of convertible promissory notes, Shares						1,358,086
Convertible preferred stock conversion price						$6.97
Stock issued for warrant exercised						305,927
InteKrin Acquisition
Related Party Transaction [Line Items]
Business Combination Consideration Transferred1							$5,000,000
Securities held by Mr.Lanfear in InteKrin Russia							10.00%

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Details) (Subsequent Events, InteKrin Therapeutics Inc, USD $)	0 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 23, 2015
Subsequent Events | InteKrin Therapeutics Inc
Subsequent Event [Line Items]
Business acquisition, number of shares issued	358,384
Fair value of contingent consideration	$9.80

Supplementary_Data_Quarterly_F2

Supplementary Data - Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Information (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$6,493	$16,052	$4,965	$3,596	$1,232	$506	$507	$506	$31,106	$2,751	$1,899
Total operating expenses	33,053	22,475	22,903	17,357	11,719	7,289	9,791	9,945	95,788	38,744	40,417
Net loss	-29,023	-7,914	-25,070	-25,170					-87,177	-53,635	-33,018
Net loss attributable to Coherus	($29,134)	($7,872)	($24,957)	($25,170)	($14,591)	($21,473)	($8,709)	($8,862)	($87,133)	($53,635)	($33,018)
Net loss per share attributable to Coherus, basic and diluted	($1.47)	($1.79)	($5.96)	($6.04)	($3.68)	($6.23)	($2.80)	($3.14)	($10.64)	($16.10)	($15.85)