Earnings per Share (Reconciliation between Basic and Diluted Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income for basic and diluted earnings per share	$ 19,036	$ 13,579	$ 37,372	$ 28,996
Basic weighted average shares outstanding	35,046	38,427	35,375	38,373
Dilutive effect of stock options and restricted stock awards	223	220	235	251
Diluted weighted average shares outstanding	35,269	38,647	35,610	38,624
Basic earnings per common share	$ 0.54	$ 0.35	$ 1.06	$ 0.76
Diluted earnings per common share	$ 0.54	$ 0.35	$ 1.05	$ 0.75