CONDENSED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 11,324	$ 12,990
Restricted cash	795	795
Current portion of marketable securities	133,869	52,234
Interest and other receivables	1,439	564
Prepaid assets	249	474
Total current assets	147,676	67,057
Noncurrent portion of marketable securities	7,464
Property and equipment, net	77	92
Deposits and other assets	191	195
Total assets	155,408	67,344
Current liabilities:
Accounts payable	1,520	1,397
Accrued compensation and benefits	1,556	3,946
Accrued restructuring charges	11	94
Accrued liabilities	1,286	1,783
Fair value of derivatives	143	367
Total current liabilities	4,516	7,587
Commitments and contingencies
Stockholders' equity:
Common stock	157	131
Additional paid-in capital	1,052,028	952,403
Accumulated deficit	(901,203)	(892,763)
Accumulated other comprehensive loss	(90)	(14)
Total stockholders' equity	150,892	59,757
Total liabilities and stockholders' equity	$ 155,408	$ 67,344