Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 10,562	$ 9,710	$ 19,221	$ 17,069
Average Common Shares:
Basic (weighted-average outstanding shares)	11,422,000	11,352,000	11,405,000	11,316,000
Dilutive potential common shares from stock options, shares	128,000	146,000	124,000	151,000
Diluted (weighted-average outstanding shares)	11,550,000	11,498,000	11,529,000	11,467,000
Basic earnings per share (in dollars per share)	$ 0.93	$ 0.86	$ 1.69	$ 1.51
Diluted earnings per share (in dollars per share)	$ 0.92	$ 0.84	$ 1.67	$ 1.49
Stock options excluded from diluted earnings per share calculation because the effect would be anti-dilutive			42,981