CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Collaboration revenues:
Product revenue	$ 2,722us-gaap_SalesRevenueGoodsNet	$ 4,812us-gaap_SalesRevenueGoodsNet
Research and development revenue	5,840us-gaap_ContractsRevenue	5,973us-gaap_ContractsRevenue
Total collaboration revenue	8,562us-gaap_Revenues	10,785us-gaap_Revenues
Operating expenses:
Research and development	22,749us-gaap_ResearchAndDevelopmentExpense	26,692us-gaap_ResearchAndDevelopmentExpense
General and administrative	7,890us-gaap_GeneralAndAdministrativeExpense	11,717us-gaap_GeneralAndAdministrativeExpense
Total operating expenses	30,639us-gaap_OperatingExpenses	38,409us-gaap_OperatingExpenses
Operating loss	(22,077)us-gaap_OperatingIncomeLoss	(27,624)us-gaap_OperatingIncomeLoss
Other income:
Interest income	112us-gaap_InvestmentIncomeInterest	200us-gaap_InvestmentIncomeInterest
Other income	88us-gaap_OtherNonoperatingIncomeExpense	62us-gaap_OtherNonoperatingIncomeExpense
Total other income	200us-gaap_NonoperatingIncomeExpense	262us-gaap_NonoperatingIncomeExpense
Net loss	(21,877)	(27,362)
Basic and diluted net loss per share (in dollars per share)	$ (0.40)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.53)us-gaap_EarningsPerShareBasicAndDiluted
Weighted average shares used in computing basic and diluted net loss per share (in shares)	54,492	51,356
Comprehensive loss:
Net loss	(21,877)	(27,362)
Net unrealized holding gains (losses) gains on available-for-sale marketable securities	18	(16)
Comprehensive loss	$ (21,859)us-gaap_ComprehensiveIncomeNetOfTax	$ (27,378)us-gaap_ComprehensiveIncomeNetOfTax

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.