Net Loss per Share (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Anti-dilutive securities excluded from the computation of diluted net loss per share
Anti-dilutive securities (in shares)			2,642	2,837
Components of basic and diluted net loss per share
Net loss	$ (16,631)	$ (16,996)	$ (58,488)	$ (61,373)
Weighted average basic common shares outstanding (in shares)	21,194	21,085	21,169	20,700
Weighted average diluted common shares outstanding (in shares)	21,194	21,085	21,169	20,700
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.78)	$ (0.81)	$ (2.76)	$ (2.96)
Options to purchase shares of common stock
Anti-dilutive securities excluded from the computation of diluted net loss per share
Anti-dilutive securities (in shares)			2,013	2,631
Shares of common stock issuable upon the vesting of restricted stock units
Anti-dilutive securities excluded from the computation of diluted net loss per share
Anti-dilutive securities (in shares)			629	206