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Investment Securities (Fair Value of Hedge Funds Subject to Restrictions on Redemption Frequency) (Details) (USD $) In Millions, unless otherwise specified | Sep. 30, 2012 | Dec. 31, 2011
--- | --- | ---
Hedge funds |  |
Investment securities |  |
Other long-term investments | $ 124.3 |
Private equity funds |  |
Investment securities |  |
Other long-term investments | 129.8 |
Hedge and private equity funds included in other long-term investments |  |
Investment securities |  |
Other long-term investments | 254.1 | 254.2
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 108.5 | 81.5
Private equity funds | Private Equity Multi Sector [Member] |  |
Investment securities |  |
Other long-term investments | 29.3 | 26.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 6.4 | 8.2
Private equity funds | Private Equity Energy Infrastructure and Services [Member] |  |
Investment securities |  |
Other long-term investments | 32.9 | 28.0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 11.7 | 9.9
Private equity funds | Private Equity Distressed Residential Real Estate [Member] |  |
Investment securities |  |
Other long-term investments | 19.2 | 27.4
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Private equity funds | Real Estate Funds [Member] |  |
Investment securities |  |
Other long-term investments | 12.2 | 9.5
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 3.3 | 3.3
Private equity funds | Private Equity Secondaries [Member] |  |
Investment securities |  |
Other long-term investments | 11.0 | 11.3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 3.2 | 4.0
Private equity funds | Private Equity Funds Multi Sector Europe [Member] |  |
Investment securities |  |
Other long-term investments | 4.3 | 7.8
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 4.9 | 4.7
Private equity funds | Private Equity Funds Manufacturing and Industrial [Member] |  |
Investment securities |  |
Other long-term investments | 10.6 | 6.2
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 29.1 | 0
Private equity funds | Private Equity Healthcare [Member] |  |
Investment securities |  |
Other long-term investments | 4.3 | 2.3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 5.4 | 7.0
Private equity funds | Private Equity Funds Multi Sector Asia [Member] |  |
Investment securities |  |
Other long-term investments | 0.4 | 3.6
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 2.7 | 2.6
Private equity funds | Private Equity Insurance [Member] |  |
Investment securities |  |
Other long-term investments | 3.2 | 3.5
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 41.3 | 41.3
Private equity funds | Venture Capital Funds [Member] |  |
Investment securities |  |
Other long-term investments | 2.4 | 2.4
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0.5 | 0.5
Private equity funds | Private equity funds |  |
Investment securities |  |
Other long-term investments | 129.8 | 128.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 108.5 | 81.5
Hedge funds | Hedge Funds, Equity [Member] |  |
Investment securities |  |
Other long-term investments | 58.6 | 48.8
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge Funds Credit and Distressed [Member] |  |
Investment securities |  |
Other long-term investments | 33.8 | 32.3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge Funds Diversified Strategies [Member] |  |
Investment securities |  |
Other long-term investments | 2.3 | 16.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge Funds Equity R E I T [Member] |  |
Investment securities |  |
Other long-term investments | 15.2 | 14.5
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge Funds Equity Activist [Member] |  |
Investment securities |  |
Other long-term investments | 14.0 | 12.3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge Funds Bank Loan [Member] |  |
Investment securities |  |
Other long-term investments | 0.4 | 0.5
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 0 | 0
Hedge funds | Hedge funds |  |
Investment securities |  |
Other long-term investments | 124.3 | 125.3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | $ 0 | $ 0

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- Definition The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=SL6742756-110258 + Details
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- Definition This element represents the total fair market value of investments in certain entities that calculate net asset value per share (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements, but may also be used in both the balance sheet and disclosure in the same submission. This item represents alternative investments as of the balance sheet date which may include investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds, and any other investment in which investee management calculates net asset value per share as the primary metric for investment value. + References No definition available. + Details
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