Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Basic and Diluted Earnings per Share [Line Items]
Net income (loss)	$ 14,716		$ (17,914)		$ 33,900		$ (12,104)
Weighted-average common shares outstanding	25,476,220		26,101,842		25,491,091		26,148,438
Weighted-average common share for EPS calculation	25,558,000		26,102,000		25,579,000		26,148,000
Basic earnings (loss) per common share	$ 0.58		$ (0.69)		$ 1.33		$ (0.46)
Diluted earnings (loss) per common share	$ 0.58		$ (0.69)		$ 1.33		$ (0.46)
Awards excluded from diluted EPS calculation	1,103,000	[1]	1,206,000	[1]	1,103,000	[1]	1,206,000	[1]
Restricted Stock Awards [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding	57,000		0		57,000		0
Options Awards [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding	25,000		0		31,000		0

[1] Outstanding awards excluded from the diluted earnings per share calculation because the effect of including them would have been anti-dilutive.