Earnings Per Common Share (Calculation of Earnings Per Share) (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	$ 11,503	$ 9,797	$ 22,513	$ 19,095
Less dividends and undistributed earnings allocated to participating securities	(34)	(33)	(73)	(73)
Net income applicable to common shareholders	$ 11,469	$ 9,764	$ 22,440	$ 19,022
Weighted average common shares outstanding - basic	16,811,000	16,678,000	16,785,000	16,653,000
Basic earnings per common share	$ 0.68	$ 0.59	$ 1.34	$ 1.14
Less dividends and undistributed earnings allocated to participating securities	$ (33)	$ (33)	$ (72)	$ (74)
Net Income (Loss) Available to Common Stockholders, Diluted	$ 11,470	$ 9,764	$ 22,441	$ 19,021
Dilutive effect of common stock equivalents	178,000	153,000	192,000	164,000
Weighted average common shares outstanding - diluted	16,989,000	16,831,000	16,977,000	16,817,000
Diluted earnings per common share	$ 0.68	$ 0.58	$ 1.32	$ 1.13
Antidilutive common stock equivalents	27,169	54,556	75,913	54,578