Securities (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($) security
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Securities available for sale and held to maturity pledged as collateral, fair value	$ 736.2	$ 346.1
Amortized cost of callable debt securities	155.6
Fair value of callable debt securities	$ 149.5
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	57	26
Minimum [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Callable debt securities, maturity period	2 months
Callable debt securities, call feature period	1 month
Maximum [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Callable debt securities, maturity period	20 years
Callable debt securities, call feature period	5 years
Individual name issuer trust preferred debt securities [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Number of individual name issuer trust preferred securities in a continuous unrealized loss position total | security	10	10
Number of companies issuing securities in continuous unrealized loss position | security	7
Amortized cost of trust preferred securities of individual name issuers that are below investment grade	$ 10.9
Unrealized losses of trust preferred securities of individual name issuers that are below investment grade	$ 1.3