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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Net income for basic and diluted earnings per share	$ 13,579	$ 13,542	$ 28,996	$ 30,886
Basic weighted average shares outstanding	38,427	37,210	38,373	37,189
Dilutive effect of stock options and restricted stock awards	220	1,579	251	1,595
Diluted weighted average shares outstanding	38,647	38,789	38,624	38,784
Basic earnings per common share	$ 0.35	$ 0.36	$ 0.76	$ 0.83
Diluted earnings per common share	$ 0.35	$ 0.35	$ 0.75	$ 0.80