Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Comprehensive Income (Loss)
Balance at Dec. 31, 2008	$ 66,175	$ 2	$ 234,412	$ 245	$ (168,484)
Balance (in shares) at Dec. 31, 2008		28,461,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options for cash	1,736		1,736
Issuance of common stock upon exercise of stock options for cash (in shares)		220,000
Stock-based compensation expense related to employee stock options	10,155		10,155
Stock-based compensation expense related to consultant stock options	80		80
Comprehensive income (loss):
Net income (loss)	(9,411)				(9,411)	(9,411)
Unrealized loss on investments	(226)			(226)		(226)
Comprehensive income (loss)	(9,637)					(9,637)
Balance at Dec. 31, 2009	68,509	2	246,383	19	(177,895)
Balance (in shares) at Dec. 31, 2009		28,681,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options for cash	2,983	1	2,982
Issuance of common stock upon exercise of stock options for cash (in shares)		327,000
Stock-based compensation expense related to employee stock options	10,344		10,344
Stock-based compensation expense related to consultant stock options	15		15
Comprehensive income (loss):
Net income (loss)	4,288				4,288	4,288
Unrealized loss on investments	(29)			(29)		(29)
Comprehensive income (loss)	4,259					4,259
Balance at Dec. 31, 2010	86,110	3	259,724	(10)	(173,607)
Balance (in shares) at Dec. 31, 2010	29,007,564	29,008,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options for cash	9,688		9,688
Issuance of common stock upon exercise of stock options for cash (in shares)		753,000
Stock-based compensation expense related to employee stock options	11,735		11,735
Comprehensive income (loss):
Net income (loss)	7,846				7,846	7,846
Unrealized loss on investments	(20)			(20)		(20)
Comprehensive income (loss)	7,826					7,826
Balance at Dec. 31, 2011	$ 115,359	$ 3	$ 281,147	$ (30)	$ (165,761)
Balance (in shares) at Dec. 31, 2011	29,761,022	29,761,000