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Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Net Income (Loss) Attributable to Noncontrolling Interest | $ (3.1) | $ (16.0) | $ 24.6 | $ (24.2)
Private equity funds |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Other long-term investments | 84.6 |  | 84.6 |
1-3 years | Private equity funds |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Other long-term investments | 23.5 |  | 23.5 |
3-5 years | Private equity funds |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Other long-term investments | 3.8 |  | 3.8 |
5-10 years | Private equity funds |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Other long-term investments | 56.3 |  | 56.3 |
Greater than 10 years | Private equity funds |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Other long-term investments | $ 1.0 |  | $ 1.0 |

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