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Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	$ (0.9)	$ 4.6	$ (8.2)	$ 4.0
Private equity funds
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	133.1		133.1
1-3 years \| Private equity funds
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	27.0		27.0
3-5 years \| Private equity funds
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	29.5		29.5
5-10 years \| Private equity funds
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	72.5		72.5
Greater than 10 years \| Private equity funds
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	$ 4.1		$ 4.1
Prospector Funds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Equity Method Investment, Aggregate Cost					$ 64.9
Variable Interest Entity, Consolidated, Carrying Amount, Assets					135.8
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities					39.8
Net Income (Loss) Attributable to Noncontrolling Interest					$ 31.1