Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Basic and Diluted Earnings per Share [Line Items]
Net income		$ 15,018	$ 10,685	$ 38,697	$ 24,016
Weighted-average common shares outstanding (in shares)		25,023,753	25,330,066	25,007,204	25,351,056
Weighted-average common share for EPS calculation (in shares)		25,287,630	25,556,627	25,132,339	25,591,258
Basic earnings per common share (in dollars per share)		$ 0.60	$ 0.42	$ 1.55	$ 0.95
Diluted earnings per common share (in dollars per share)		$ 0.59	$ 0.42	$ 1.54	$ 0.94
Awards excluded from diluted earnings per share calculation (in shares)	[1]	431,599	904,580	443,596	904,580
Restricted Stock Awards [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)		125,135	114,313	125,135	114,313
Stock Options [Member]
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)		138,742	112,248	0	125,889

[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.