Consolidated Statements Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2011	$ 102,690	$ 4	$ 287,792	$ (407)	$ (184,699)
Beginning balance (shares) at Dec. 31, 2011		35,996
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common warrants (shares)		3
Exercise of stock options	1,257		1,257
Exercise of stock options (shares)		708
Cancellation of shares	(65)		(65)
Cancellation of shares (shares)		(17)
Release of stock awards (shares)		982
Employee stock-based compensation	5,040		5,040
Non-employee stock-based compensation	104		104
Non-employee stock-based compensation (shares)		20
Total comprehensive loss	(30,586)			271	(30,857)
Ending balance at Dec. 31, 2012	78,440	4	294,128	(136)	(215,556)
Ending balance (shares) at Dec. 31, 2012		37,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	318		318
Exercise of stock options (shares)		326
Cancellation of shares	(465)		(465)
Cancellation of shares (shares)		(75)
Release of stock awards (shares)		408
Employee stock-based compensation	4,366		4,366
Non-employee stock-based compensation	23		23
Total comprehensive loss	(41,199)			104	(41,303)
Ending balance at Dec. 31, 2013	41,483	4	298,370	(32)	(256,859)
Ending balance (shares) at Dec. 31, 2013		38,351
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	195		195
Exercise of stock options (shares)		146
Cancellation of shares	(806)		(806)
Cancellation of shares (shares)		(456)
Release of stock awards (shares)		1,522
Employee stock-based compensation	4,608		4,608
Non-employee stock-based compensation	12		12
Total comprehensive loss	(19,181)			(110)	(19,071)
Ending balance at Dec. 31, 2014	$ 26,311	$ 4	$ 302,379	$ (142)	$ (275,930)
Ending balance (shares) at Dec. 31, 2014		39,563