Statements Of Changes In Stockholders' Equity (USD $) In Thousands, except Share data	Issuance Of Common Stock In April [Member] Common Stock [Member]	Issuance Of Common Stock In April [Member] Additional Paid-In Capital [Member]	Issuance Of Common Stock In April [Member]	Issuance Of Common Stock In October [Member] Common Stock [Member]	Issuance Of Common Stock In October [Member] Additional Paid-In Capital [Member]	Issuance Of Common Stock In October [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2008							$ 81	$ 379,042	$ (299,659)	$ 79,464
Balance, shares at Dec. 31, 2008							81,238,812
Issuance of common stock upon exercise of stock options for cash							1	4,682		4,683
Issuance of common stock upon exercise of stock options for cash, shares							1,241,034
Issuance of common stock upon exercise of purchase rights								229		229
Issuance of common stock upon exercise of purchase rights, shares							42,063
Issuance of common stock, net of offering costs	8	46,949	46,957	14	93,070	93,084
Issuance of common stock, net of offering costs, shares	7,750,000			14,000,000
Forfeiture of restricted stock, shares							(37,500)
Stock compensation expense								8,680		8,680
Net loss									(73,553)	(73,553)
Balance at Dec. 31, 2009							104	532,652	(373,212)	159,544
Balance, shares at Dec. 31, 2009							104,234,409
Issuance of common stock upon exercise of stock options for cash							1	4,084		4,085
Issuance of common stock upon exercise of stock options for cash, shares							1,104,474
Issuance of common stock upon exercise of purchase rights								528		528
Issuance of common stock upon exercise of purchase rights, shares							115,797
Issuance of common stock upon vesting of restricted stock units, shares							38,866
Other								32		32
Stock compensation expense								11,426		11,426
Net loss									(77,417)	(77,417)
Balance at Dec. 31, 2010							105	548,722	(450,629)	98,198
Balance, shares at Dec. 31, 2010							105,493,546			105,493,546
Issuance of common stock upon exercise of stock options for cash								14		14
Issuance of common stock upon exercise of stock options for cash, shares							4,893
Issuance of common stock upon exercise of purchase rights								159		159
Issuance of common stock upon exercise of purchase rights, shares							100,954
Issuance of common stock upon vesting of restricted stock units							1	(1)
Issuance of common stock upon vesting of restricted stock units, shares							666,133
Forfeiture of restricted stock, shares							(5,000)
Other								(113)		(113)
Stock compensation expense								11,573		11,573
Net loss									(30,527)	(30,527)
Balance at Dec. 31, 2011							$ 106	$ 560,354	$ (481,156)	$ 79,304
Balance, shares at Dec. 31, 2011							106,260,526			106,260,526