Consolidated Statements of Stockholders' Equity (Unaudited) (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)	Treasury Stock
Balance, value at Dec. 31, 2013	$ 170,163	$ 514	$ 1,175,108	$ (1,003,958)	$ 2	$ (1,503)
Balance, shares at Dec. 31, 2013		514,349
Stock-based compensation	2,250	0	2,250	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		1,435
Issuance of common stock under Equity Incentive Plans, value	76	2	74	0	0	0
Repurchase of common stock	(887)	0	0	0	0	(887)
Net loss	(30,835)	0	0	(30,835)	0	0
Unrealized gain on investments	8	0	0	0	8	0
Balance, value at Mar. 31, 2014	140,775	516	1,177,432	(1,034,793)	10	(2,390)
Balance, shares at Mar. 31, 2014		515,784
Balance, value at Dec. 31, 2014	284,018	726	1,389,997	(1,104,252)	(63)	(2,390)
Balance, shares at Dec. 31, 2014		725,641
Stock-based compensation	1,953	0	1,953	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		1,166
Issuance of common stock under Equity Incentive Plans, value	0	1	(1)	0	0	0
Repurchase of common stock	(357)	0	0	0	0	(357)
Net loss	(28,076)	0	0	(28,076)	0	0
Unrealized gain on investments	86	0	0	0	86	0
Other	(17)	0	(17)	0	0	0
Balance, value at Mar. 31, 2015	$ 257,607	$ 727	$ 1,391,932	$ (1,132,328)	$ 23	$ (2,747)
Balance, shares at Mar. 31, 2015		726,807