CONDENSED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 10,182	$ 42,796
Restricted cash	266	266
Marketable securities	135,655	108,645
Interest and other receivables	1,190us-gaap_NontradeReceivablesCurrent	963us-gaap_NontradeReceivablesCurrent
Prepaid assets	604us-gaap_PrepaidExpenseCurrent	736us-gaap_PrepaidExpenseCurrent
Total current assets	147,897us-gaap_AssetsCurrent	153,406us-gaap_AssetsCurrent
Noncurrent marketable securities	17,739	18,932
Property and equipment, net	171us-gaap_PropertyPlantAndEquipmentNet	173us-gaap_PropertyPlantAndEquipmentNet
Total assets	165,807us-gaap_Assets	172,511us-gaap_Assets
Current liabilities:
Accounts payable	1,180us-gaap_AccountsPayableCurrent	1,033us-gaap_AccountsPayableCurrent
Accrued compensation and benefits	2,135	4,213
Accrued collaboration charges	626
Accrued restructuring charges	316us-gaap_RestructuringReserveCurrent
Accrued liabilities	1,375us-gaap_AccruedLiabilitiesCurrent	1,537us-gaap_AccruedLiabilitiesCurrent
Deferred revenue	35,000us-gaap_DeferredRevenueCurrent	35,000us-gaap_DeferredRevenueCurrent
Fair value of derivatives		16
Total current liabilities	40,632us-gaap_LiabilitiesCurrent	41,799us-gaap_LiabilitiesCurrent
Commitments and contingencies
Stockholders' equity:
Common stock	158us-gaap_CommonStockValue	157us-gaap_CommonStockValue
Additional paid-in capital	1,062,782	1,059,072
Accumulated deficit	(937,748)	(928,433)
Accumulated other comprehensive loss	(17)	(84)
Total stockholders' equity	125,175us-gaap_StockholdersEquity	130,712us-gaap_StockholdersEquity
Total liabilities and stockholders' equity	$ 165,807	$ 172,511

Carrying value as of the balance sheet date of obligations incurred and payable to collaboration partner for which invoices have not yet been received under the respective collaboration agreement (due within one year or within the normal operating cycle if longer).

No definition available.