Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income		$ 14,756	$ 13,367	$ 31,825	$ 29,800
Average Common Shares:
Basic (weighted-average outstanding shares)		11,380,000	12,050,000	11,337,000	12,077,000
Dilutive potential common shares from stock options, shares		116,000	156,000	140,000	174,000
Diluted (weighted-average outstanding shares)		11,496,000	12,206,000	11,477,000	12,251,000
Basic earnings per share (in dollars per share)		$ 1.30	$ 1.11	$ 2.81	$ 2.47
Diluted earnings per share (in dollars per share)		$ 1.28	$ 1.10	$ 2.77	$ 2.43
Stock options excluded from diluted earnings per share calculation because the effect would be anti-dilutive				51,909
Treasury Stock, Shares, Retired	849,690