Investment Securities (Gains and Losses on Sales) (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Gross Gains on Sales of Investment Securities	$ 12,467	$ 11,180	$ 11,640
Gross Losses on Sales of Investment Securities	(2,037)	(977)	(1,480)
Net Gains on Sales of Investment Securities	10,430	10,203	10,160
Tax on Sale of Investment Securities	$ 4,100	$ 4,000	$ 4,000