Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 9,710	$ 9,195	$ 17,069	$ 16,433
Average Common Shares:
Basic (weighted-average outstanding shares)	11,352,000	12,097,000	11,316,000	12,090,000
Dilutive potential common shares from stock options, shares	146,000	179,000	151,000	183,000
Diluted (weighted-average outstanding shares)	11,498,000	12,276,000	11,467,000	12,273,000
Basic earnings per share (in dollars per share)	$ 0.86	$ 0.76	$ 1.51	$ 1.36
Diluted earnings per share (in dollars per share)	$ 0.84	$ 0.75	$ 1.49	$ 1.34
Stock options excluded from diluted earnings per share calculation because the effect would be anti-dilutive			33,325