(Loss) Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
(Loss) Earnings Per Share
Net (loss) income for basic and diluted earnings per share (in dollars)	$ (6,453)	$ 232	$ (247,096)	$ 5,458	$ (3,672)	$ 10,477	$ (196,143)	$ 9,549	$ (247,859)	$ (179,789)	$ 23,980
Shares of common stock and common stock equivalents:
Weighted average shares-basic	38,418,000	38,301,000	38,607,000	39,112,000	39,624,000	40,615,000	41,112,000	41,435,000	38,418,000	40,691,000	42,767,000
Effect of dilutive securities (in shares)											729,000
Weighted average shares-diluted	38,418,000	39,252,000	38,607,000	40,303,000	39,624,000	41,271,000	41,112,000	42,180,000	38,418,000	40,691,000	43,496,000
(Loss) earnings per share:
Basic (in dollars per share)	$ (0.17)	$ 0.01	$ (6.40)	$ 0.14	$ (0.09)	$ 0.26	$ (4.77)	$ 0.23	$ (6.45)	$ (4.42)	$ 0.56
Diluted (in dollars per share)	$ (0.17)	$ 0.01	$ (6.40)	$ 0.14	$ (0.09)	$ 0.25	$ (4.77)	$ 0.23	$ (6.45)	$ (4.42)	$ 0.55
Anti-dilutive equity awards not included in the detailed earnings per share computation
Equity awards not included in the diluted earnings per share computation									1,700,000	2,000,000	600,000