Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 8,659	$ 7,359
Average Common Shares:
Basic (weighted-average outstanding shares)	11,389,000	11,280,000
Dilutive potential common shares from stock options, shares	118,000	156,000
Diluted (weighted-average outstanding shares)	11,507,000	11,436,000
Basic earnings per share (in dollars per share)	$ 0.76	$ 0.65
Diluted earnings per share (in dollars per share)	$ 0.75	$ 0.64
Stock options excluded from diluted earnings per share calculation because the effect would be anti-dilutive	85,962