Consolidated Investment Products (Fair Value Hierarchy Levels Of Investments Held And Notes Issued By Consolidated Investment Products) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
CLO-related derivative assets		$ 10.8
Total assets at fair value	1,786.6	1,752.2
Liabilities	8,443.4	10,209.4
CLO-related derivative liabilities		(5.8)
Total liabilities at fair value	(1,158.5)	(1,261.3)
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
CLO-related derivative assets		0
Total assets at fair value	1,776.1	1,751.1
CLO-related derivative liabilities		0
Total liabilities at fair value	(1,155.1)	(1,244.5)
Significant Other Observable Inputs (Level 2) [Member]
CLO-related derivative assets		10.8
Total assets at fair value	1.8	1.1
CLO-related derivative liabilities		(5.8)
Total liabilities at fair value	0	0
Significant Unobservable Inputs (Level 3) [Member]
Real Estate Investments, Net	5.3
Private Equity Fund Assets	94.1
CLO-related derivative assets		0
Total assets at fair value	8.7	0
CLO-related derivative liabilities		0
Total liabilities at fair value	(3.4)	(16.8)
Bank Loans [Member]
Investments fair value	3,709.3	5,354.3
Bank Loans [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	0	0
Bank Loans [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	3,709.3	5,354.3
Bank Loans [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	0	0
Bonds [Member]
Investments fair value	185.4	292.8
Bonds [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	0	0
Bonds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	185.4	292.8
Bonds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	0	0
Equity Securities [Member]
Investments fair value	12.1	35.3
Equity Securities [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	0	0
Equity Securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	12.1	35.3
Equity Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	0	0
Private Equity Fund, Equity Securities [Member]
Investments fair value	124.4	138.2
Private Equity Fund, Equity Securities [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	20.4	11.4
Private Equity Fund, Equity Securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	9.9	0.1
Private Equity Fund, Equity Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value		126.7
Debt Securities [Member]
Investments fair value		10.0
Debt Securities [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value		0
Debt Securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value		0
Debt Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value		10.0
Investments in Other Private Equity Funds [Member]
Investments fair value	503.5	559.5
Investments in Other Private Equity Funds [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	0	0
Investments in Other Private Equity Funds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	0	0
Investments in Other Private Equity Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	503.5	559.5
Debt Securities Issued By U.S. Treasury [Member]
Investments fair value	10.0	6.0
Debt Securities Issued By U.S. Treasury [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	10.0	6.0
Debt Securities Issued By U.S. Treasury [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	0	0
Debt Securities Issued By U.S. Treasury [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	0	0
Real Estate Investment [Member]
Investments fair value		232.9
Real Estate Investment [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investments fair value	0	0
Real Estate Investment [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Investments fair value	0	0
Real Estate Investment [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Investments fair value	5.3	232.9
Consolidated Investment Products [Member]
Liabilities	3,994.8	5,668.4
Consolidated Investment Products [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total assets at fair value	30.4	17.4
Total liabilities at fair value	0	0
Consolidated Investment Products [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Total assets at fair value	3,916.7	5,693.3
Total liabilities at fair value	0	(5.8)
Consolidated Investment Products [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Total assets at fair value	602.9	929.1
Total liabilities at fair value	(3,899.4)	(5,512.9)
Consolidated Investment Products [Member] \| Fair Value [Member]
Total assets at fair value	4,550.0	6,639.8
Total liabilities at fair value	(3,899.4)	(5,518.7)
CLO [Member]
Notes payable fair value		(5,512.9)
CLO [Member] \| Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Notes payable fair value	0	0
CLO [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Notes payable fair value	0	0
CLO [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Notes payable fair value	$ (3,899.4)	$ (5,512.9)

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- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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Amount of real estate investments, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; (7) other real estate investments; (8) real estate joint ventures; and (9) unconsolidated real estate and other joint ventures not separately presented.

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