Earnings per Share (Reconciliation between Basic and Diluted Earnings per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income for basic and diluted earnings per share	$ 18,015	$ 13,143	$ 47,011	$ 44,029
Basic weighted average shares outstanding	38,050	37,919	38,264	37,435
Dilutive effect of stock options and restricted stock awards	203	532	235	1,241
Diluted weighted average shares outstanding	38,253	38,451	38,499	38,676
Basic earnings per common share	$ 0.47	$ 0.35	$ 1.23	$ 1.18
Diluted earnings per common share	$ 0.47	$ 0.34	$ 1.22	$ 1.14