(Loss) Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
(Loss) Earnings Per Share
Net (loss) income for basic and diluted earnings per share (in dollars)	$ (3,672)	$ 10,477	$ (196,143)	$ 9,549	$ 1,830	$ 6,210	$ 7,508	$ 8,432	$ (179,789)	$ 23,980	$ 42,834
Shares of common stock and common stock equivalents:
Weighted average shares - basic	39,624,000	40,615,000	41,112,000	41,435,000	41,636,000	42,407,000	43,226,000	43,827,000	40,691,000	42,767,000	43,538,000
Effect of dilutive securities (in shares)										729,000	480,000
Weighted average shares-diluted	39,624,000	41,271,000	41,112,000	42,180,000	42,538,000	42,941,000	43,704,000	44,415,000	40,691,000	43,496,000	44,018,000
(Loss) earnings per share:
Basic (in dollars per share)	$ (0.09)	$ 0.26	$ (4.77)	$ 0.23	$ 0.04	$ 0.15	$ 0.17	$ 0.19	$ (4.42)	$ 0.56	$ 0.98
Diluted (in dollars per share)	$ (0.09)	$ 0.25	$ (4.77)	$ 0.23	$ 0.04	$ 0.14	$ 0.17	$ 0.19	$ (4.42)	$ 0.55	$ 0.97
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)									2,000,000	600,000	700,000