Securities (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) issuance security	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds | $	$ 30,403	$ 124,142	$ 95,375
Number Of Issuances Of Securities Exceeding Shareholders Equity Threshold | issuance	0
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	1
Number Of Securities In Continuous Loss Position For Twelve Months or More	0
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Issuances Of Securities Exceeding Shareholders Equity Threshold, Percent	10.00%
Number Of Securities In Unrealized Loss Position	2
Number Of Securities In Continuous Loss Position For Twelve Months or More	2
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	396
Number Of Securities In Continuous Loss Position For Twelve Months or More	120
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	314
Number Of Securities In Continuous Loss Position For Twelve Months or More	69
US Government Corporations and Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	44
Number Of Securities In Continuous Loss Position For Twelve Months or More	16