Consolidated Statements of Convertible Preferred Stock and Stockholders' (Deficit) (USD $) In Thousands, except Share data	Total	Convertible Preferred Stock	Convertible Preferred Stock Series E Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balances at Dec. 31, 2009	$ (65,781)	$ 83,178		$ 1	$ 1,634	$ 10	$ (67,426)
Beginning balances (in shares) at Dec. 31, 2009		10,657,030		1,509,841
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)				346,924
Issuance of common stock upon exercise of options and vesting of stock awards	192			1	191
Employee stock-based compensation expense	299				299
Comprehensive loss	(5,113)					(13)	(5,100)
Ending balance at Dec. 31, 2010	(70,403)	83,178		2	2,124	(3)	(72,526)
Ending balance (in shares) at Dec. 31, 2010		10,657,030		1,856,765
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)				129,666
Issuance of common stock upon exercise of options and vesting of stock awards	67				67
Employee stock-based compensation expense	221				221
Comprehensive loss	(2,230)					2	(2,232)
Ending balance at Dec. 31, 2011	(72,345)	83,178		2	2,412	(1)	(74,758)
Ending balance (in shares) at Dec. 31, 2011		10,657,030		1,986,431
Issuance of Series E convertible preferred stock, net of issuance costs of $1,404 (in shares)			1,672,300
Issuance of Series E convertible preferred stock, net of issuance costs of $1,404			18,845
Issuance of common stock upon exercise of options and vesting of stock awards (in shares)				200,264
Issuance of common stock upon exercise of options and vesting of stock awards	84				84
Employee stock-based compensation expense	821				821
Comprehensive loss	(23,504)					5	(23,509)
Ending balance at Dec. 31, 2012	$ (94,944)	$ 102,023		$ 2	$ 3,317	$ 4	$ (98,267)
Ending balance (in shares) at Dec. 31, 2012		12,329,330		2,186,695