Earnings per Share (Reconciliation between Basic and Diluted Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income for basic and diluted earnings per share	$ 20,232	$ 18,015	$ 57,604	$ 47,011
Basic weighted average shares outstanding	34,304	38,050	35,014	38,264
Dilutive effect of stock options and restricted stock awards	211	203	227	235
Diluted weighted average shares outstanding	34,515	38,253	35,241	38,499
Basic earnings per common share	$ 0.59	$ 0.47	$ 1.65	$ 1.23
Diluted earnings per common share	$ 0.59	$ 0.47	$ 1.63	$ 1.22