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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income for basic and diluted earnings per share	$ 24,067	$ 20,232	$ 69,218	$ 57,604
Basic weighted average shares outstanding	32,421	34,304	32,716	35,014
Dilutive effect of stock options and restricted stock awards	284	211	278	227
Diluted weighted average shares outstanding	32,705	34,515	32,994	35,241
Basic earnings per common share	$ 0.74	$ 0.59	$ 2.12	$ 1.65
Diluted earnings per common share	$ 0.74	$ 0.59	$ 2.10	$ 1.63