Investment Securities (Significant Unobservable Inputs) (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) Investment	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) Investment	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) input Investment
Quantitative information for Level 3 Fair Value Measurements Assets
Equity in earnings of unconsolidated affiliates, net of tax	$ 0.0	$ 3.9	$ 0.0	$ 18.0
Number of Investments with Significant Unobseravble Inputs | Investment	1		1		1
NR | Preferred Stock | Par Value [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure					$ 70.0
NR | Preferred Stock | Issuer's intent to call [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Fair Value Measurements, Valuation Techniques					70.0
NR | Convertible Preferred Stock [Member] | Multiple of EBITA [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Unobservable Inputs | input					0
Fair Value Measurements, Valuation Techniques					6.0
NR | Convertible Preferred Stock [Member] | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure					$ 5.7
NR | Seller Priority Surplus Note [Member] | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	$ 49.0		$ 49.0		$ 38.0
Timing of interest payments			5 years		5 years
Timing of principal payments			10 years		10 years
Fair Value Measurements, Valuation Techniques			0.095		0.13
NR | Pari Passu Surplus Note [Member] | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	22.5		$ 22.5		$ 13.5
Timing of interest payments			5 years		5 years
Timing of principal payments			15 years		15 years
Fair Value Measurements, Valuation Techniques			0.158		0.224
AAA | Mortgage-backed and asset-backed securities | Broker Pricing [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	36.0		$ 36.0
Standard & Poor's, AA+ Rating [Member] | Residential Mortgage Backed Securities | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Conditional Prepayment Rate			1.50%
MSA [Member] | NR | Preferred Stock | Discounted cash flows
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	71.6		$ 71.6
Fair Value Measurements, Valuation Techniques			0.06245
PassportCard [Member] | NR | Private equity funds | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	21.0		$ 21.0		$ 21.0
PassportCard [Member] | NR | Private equity funds | Average Share Price [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Fair Value Measurements, Valuation Techniques			1		1.00
Compare.com [Member] | NR | Private equity funds | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	33.8		$ 33.8
Compare.com [Member] | NR | Private equity funds | Average Share Price [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Fair Value Measurements, Valuation Techniques			1.03
Compare.com [Member] | NR | Private equity funds | Recent Transaction Two [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure					$ 33.8
Fair Value Measurements, Valuation Techniques					1.03
OneTitle [Member] | NR | Private equity funds | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	3.2		$ 3.2
OneTitle [Member] | NR | Private equity funds | Average Share Price [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Fair Value Measurements, Valuation Techniques			2.521
Galvanic [Member] | NR | Convertible Preferred Stock [Member] | Multiple of EBITA [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Fair Value Measurements, Valuation Techniques			6
Galvanic [Member] | NR | Convertible Preferred Stock [Member] | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	6.1		$ 6.1
Captricity [Member] | NR | Convertible Preferred Stock [Member] | Recent transaction [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	$ 27.0		$ 27.0		$ 27.0
Fair Value Measurements, Valuation Techniques			3.83		3.83
durchblicker.at [Member] | NR | Private equity funds
Quantitative information for Level 3 Fair Value Measurements Assets
Time Until Expiration of Security			4 years		4 years
Volatility Rate	60.00%		60.00%		60.00%
Risk Free Rate	1.15%		1.15%		1.15%
durchblicker.at [Member] | NR | Private equity funds | Option pricing method [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Assets, Fair Value Disclosure	$ 9.9		$ 9.9		$ 9.6
Standard & Poor's, B Rating [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Basis points			2.50%
Standard & Poor's, CCC Rating [Member]
Quantitative information for Level 3 Fair Value Measurements Assets
Basis points					2.50%