Investment Securities (Securities classified as level 3) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Significant unobservable inputs
Number of Securities in each Asset type	1
Standard & Poor's, AAA Rating [Member] | Commercial | Broker Indication [Member]
Significant unobservable inputs
Assets, Fair Value Disclosure	$ 6.4	[1],[2]
Default rate	0.80%
Standard & Poor's, AA+ Rating [Member] | Mortgage-backed and asset-backed securities | Broker Pricing [Member]
Significant unobservable inputs
Assets, Fair Value Disclosure	10.9	[1],[2]
Standard Poors N R Rating [Member] | Preferred stocks | Discounted cash flow
Significant unobservable inputs
Discount Rate	6.90%
Standard & Poor's, BBB- Rating [Member] | Commercial | Broker Pricing [Member]
Significant unobservable inputs
Assets, Fair Value Disclosure	$ 1.1	[1],[2]

[1] Credit ratings are assigned based on the following hierarchy: 1) Standard & Poor's and 2) Moody's

[2] As of March 31, 2014, each asset type consists of one security.