Net Income (Loss) Per Share (Computation of Basic and Diluted Net Income (Loss) per Share) (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Net Income (Loss) Per Share
Net income (loss)	$ 2,166	$ (117)	$ 26,894	$ (2,568)
Weighted average common stock outstanding (basic)	41,202,939	40,271,983	41,035,681	40,182,567
Common equivalent shares from options to purchase common stock and restricted common stock units	1,347,459		1,244,305
Weighted average common stock outstanding (diluted)	42,550,398	40,271,983	42,279,986	40,182,567
Basic net income (loss) per share	$ 0.05	$ 0.00	$ 0.66	$ (0.06)
Diluted net income (loss) per share	$ 0.05	$ 0.00	$ 0.64	$ (0.06)