Securities (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) issuance security	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds | $	$ 124.1	$ 95.4	$ 63.3
Number Of Issuances Of Securities Exceeding Shareholders Equity Threshold | issuance	0
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	22
Number Of Securities In Continuous Loss Position For Twelve Months or More	0
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	1
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	1
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	192
Number Of Securities In Continuous Loss Position For Twelve Months or More	50
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number Of Securities In Unrealized Loss Position	180
Number Of Securities In Continuous Loss Position For Twelve Months or More	5