Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Basic and Diluted Earnings per Share [Line Items]
Net income	$ 13,331		$ 22,393
Weighted-average common shares outstanding (in shares)	25,372,280		25,245,497
Weighted-average common share for EPS calculation (in shares)	25,590,207		25,340,669
Basic earnings per common share (in dollars per share)	$ 0.53		$ 0.89
Diluted earnings per common share (in dollars per share)	$ 0.52		$ 0.88
Awards excluded from diluted earnings per share calculation(1)	908,480	[1]	643,066	[1]
Restricted Stock Awards [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)	102,635		79,787
Stock Options [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)	115,292		15,385

[1] Outstanding awards that are not "in-the-money" are excluded from the diluted earnings per share calculation because the effect of including them would have been anti-dilutive.