CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2009	$ 64,701	$ 312	$ 117,941	$ 41	$ (53,593)
Balance (in shares) at Dec. 31, 2009		31,224
Increase (Decrease) in Stockholders' Equity
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards	2,191	10	2,181
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards (in shares)		1,046
Issuance of common stock, net of costs of $46	19,966	50	19,916
Issuance of common stock, net of costs (in shares)		4,955
Stock-based compensation	3,298		3,298
Other comprehensive loss-change in unrealized gain (loss) on available-for-sale investments	(37)			(37)
Net income (loss)	(23,062)				(23,062)
Balance at Dec. 31, 2010	67,057	372	143,336	4	(76,655)
Balance (in shares) at Dec. 31, 2010		37,225
Increase (Decrease) in Stockholders' Equity
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards	3,403	12	3,391
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards (in shares)		1,198
Stock-based compensation	3,780		3,780
Other comprehensive loss-change in unrealized gain (loss) on available-for-sale investments	(3)			(3)
Net income (loss)	11,256				11,256
Balance at Dec. 31, 2011	85,493	384	150,507	1	(65,399)
Balance (in shares) at Dec. 31, 2011	38,423	38,423
Increase (Decrease) in Stockholders' Equity
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards	3,646	19	3,627
Issuance of common stock for exercise of options, employee stock purchase plan and release of awards (in shares)		1,881
Repurchase of common stock	(828)	(2)	(826)
Repurchase of common stock (in shares)		(250)
Stock-based compensation	3,835		3,835
Other comprehensive loss-change in unrealized gain (loss) on available-for-sale investments	10			10
Net income (loss)	(27,614)				(27,614)
Balance at Dec. 31, 2012	$ 64,542	$ 401	$ 157,143	$ 11	$ (93,013)
Balance (in shares) at Dec. 31, 2012	40,054	40,054