Earnings 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
Earnings Per Share
Net (loss) income for basic and diluted earnings per share (in dollars)	$ 10,477	$ 6,210	$ (176,117)	$ 22,150
Shares of common stock and common stock equivalents:
Average common shares used in basic computation (in shares)	40,615	42,407	41,051	43,148
Effect of dilutive securities (in shares)	656	534		628
Average common shares used in diluted computation (in shares)	41,271	42,941	41,051	43,776
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.26	$ 0.15	$ (4.29)	$ 0.51
Diluted (in dollars per share)	$ 0.25	$ 0.14	$ (4.29)	$ 0.51
Anti-dilutive equity awards not included in the detailed earnings per share computation
Equity awards not included in the detailed earnings per share computation (in shares)	1,451	680	2,233	657