Securities (Narrative) (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]	Sep. 30, 2013 Nonaccrual Investment Security [Member] Preferred Term Security [PreTSL] XXV, tranche C1 [Member] Trust preferred securities: Collateralized debt obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Other Than Temporary Impairment Credit Losses Previously Recognized In Earnings					$ 1.2
Securities in unrealized loss position, number of companies issuing securities	7
Fair Value of Available for Sale and Held to Maturity securities pledged as collateral	391.7	386.5
Amortized cost of trust preferred securities of individual name issuers that are below investment grade	11.9
Unrealized losses of trust preferred securities of individual name issuers that are below investment grade	2.1
Amortized cost of callable debt securities	111.4
Fair value of callable debt securities	$ 106.7
Callable Debt Securities, Maturity Period			2 years	24 years