Statement Of Shareholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]	Total
Balances at Dec. 31, 2009	$ 187,895	$ (172,202)	$ 33	$ 15,726
Beginning Balance, Shares at Dec. 31, 2009	52,200,358
Issuance of common stock upon exercise of options, Shares	458,962
Issuance of common stock upon exercise of options	1,034			1,034
Issuance of common stock under employee stock purchase plan, Shares	298,467
Issuance of common stock under employee stock purchase plan	383			383
Stock-based compensation	2,031			2,031
Net income (loss)		3,896		3,896
Unrealized gains (losses) on available-for-sale securities			36	36
Comprehensive income (loss)				3,932
Balances at Dec. 31, 2010	191,343	(168,306)	69	23,106
Ending Balance, Shares at Dec. 31, 2010	52,957,787
Issuance of common stock upon exercise of options, Shares	2,379,116			2,379,116
Issuance of common stock upon exercise of options	7,588			7,588
Issuance of common stock under employee stock purchase plan, Shares	169,217
Issuance of common stock under employee stock purchase plan	711			711
Stock-based compensation	3,869			3,869
Net income (loss)		70,726		70,726
Unrealized gains (losses) on available-for-sale securities			(82)	(82)
Comprehensive income (loss)				70,644
Balances at Dec. 31, 2011	203,511	(97,580)	(13)	105,918
Ending Balance, Shares at Dec. 31, 2011	55,506,120			55,506,120
Issuance of common stock upon exercise of options, Shares	628,394			628,394
Issuance of common stock upon exercise of options	1,835			1,835
Issuance of common stock under employee stock purchase plan, Shares	203,389
Issuance of common stock under employee stock purchase plan	851			851
Issuance of common stock in conjunction with vesting of restricted stick units, Shares	45,810
Issuance of common stock in conjunction with vesting of restricted stick units	278			278
Stock-based compensation	4,791			4,791
Net income (loss)		(29,781)		(29,781)
Unrealized gains (losses) on available-for-sale securities			44	44
Comprehensive income (loss)				(29,737)
Balances at Dec. 31, 2012	$ 211,266	$ (127,361)	$ 31	$ 83,936
Ending Balance, Shares at Dec. 31, 2012	56,383,713			56,383,713