Earnings Per Common Share (Summary Of Computation Of Basic And Diluted Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Income available to common shareholders	$ 31,123	$ 20,267
Denominator for basic earnings per share (weighted average common shares outstanding)	15,288,332	15,312,059
Effect of dilutive options and warrants	142,996	120,710
Denominator for diluted earnings per share (weighted average common shares outstanding adjusted for the effect of dilutive options and warrants)	15,431,328	15,432,769
Basic earnings per common share	$ 2.04	$ 1.32
Diluted earnings per common share	$ 2.02	$ 1.31