Consolidated Investment Products (Fair Value Hierarchy Levels Of Investments Held And Notes Issued By Consolidated Investment Products) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
CLO notes	$ (8,663.6)	$ (10,209.4)
Fair Value Measurements [Member]
CLO-related derivative assets		10.8
Private equity fund assets	124.7	138.2
Real estate investments	153.6	232.9
Total assets at fair value	4,717.9	6,639.8
CLO-related derivative liabilities		(5.8)
Total liabilities at fair value	(3,855.0)	(5,518.7)
Quoted Prices in Active Markets for Identical Assets [Member]
CLO-related derivative assets		0
Private equity fund assets	16.4	11.4
Real estate investments	0	0
Total assets at fair value	26.4	17.4
CLO-related derivative liabilities		0
Total liabilities at fair value	0	0
Significant Other Observable Inputs [Member]
CLO-related derivative assets		10.8
Private equity fund assets	0	0.1
Real estate investments	0	0
Total assets at fair value	3,894.9	5,693.3
CLO-related derivative liabilities		(5.8)
Total liabilities at fair value	0	(5.8)
Significant Unobservable Inputs [Member]
CLO-related derivative assets		0
Private equity fund assets	108.3	126.7
Real estate investments	153.6	232.9
Total assets at fair value	796.6	929.1
CLO-related derivative liabilities		0
Total liabilities at fair value	(3,855.0)	(5,512.9)
Bank Loans [Member] | Fair Value Measurements [Member]
CLO collateral assets	3,711.5	5,354.3
Bank Loans [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
CLO collateral assets	0	0
Bank Loans [Member] | Significant Other Observable Inputs [Member]
CLO collateral assets	3,711.5	5,354.3
Bank Loans [Member] | Significant Unobservable Inputs [Member]
CLO collateral assets	0	0
Bonds [Member] | Fair Value Measurements [Member]
CLO collateral assets	171.8	292.8
Bonds [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
CLO collateral assets	0	0
Bonds [Member] | Significant Other Observable Inputs [Member]
CLO collateral assets	171.8	292.8
Bonds [Member] | Significant Unobservable Inputs [Member]
CLO collateral assets	0	0
Equity Securities [Member] | Fair Value Measurements [Member]
CLO collateral assets	11.6	35.3
Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
CLO collateral assets	0	0
Equity Securities [Member] | Significant Other Observable Inputs [Member]
CLO collateral assets	11.6	35.3
Equity Securities [Member] | Significant Unobservable Inputs [Member]
CLO collateral assets	0	0
Debt Securities [Member]
Investments, Fair Value Disclosure		10.0
Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
Investments, Fair Value Disclosure		0
Debt Securities [Member] | Significant Other Observable Inputs [Member]
Investments, Fair Value Disclosure		0
Debt Securities [Member] | Significant Unobservable Inputs [Member]
Investments, Fair Value Disclosure		10.0
Investments in Other Private Equity Funds [Member] | Fair Value Measurements [Member]
Private equity fund assets	534.7	559.5
Investments in Other Private Equity Funds [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
Private equity fund assets	0	0
Investments in Other Private Equity Funds [Member] | Significant Other Observable Inputs [Member]
Private equity fund assets	0	0
Investments in Other Private Equity Funds [Member] | Significant Unobservable Inputs [Member]
Private equity fund assets	534.7	559.5
Debt Securities Issued By U.S. Treasury [Member] | Fair Value Measurements [Member]
Private equity fund assets	10.0	6.0
Debt Securities Issued By U.S. Treasury [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
Private equity fund assets	10.0	6.0
Debt Securities Issued By U.S. Treasury [Member] | Significant Other Observable Inputs [Member]
Private equity fund assets	0	0
Debt Securities Issued By U.S. Treasury [Member] | Significant Unobservable Inputs [Member]
Private equity fund assets	0	0
CLO Notes [Member] | Fair Value Measurements [Member]
CLO notes	(3,855.0)	(5,512.9)
CLO Notes [Member] | Quoted Prices in Active Markets for Identical Assets [Member]
CLO notes	0	0
CLO Notes [Member] | Significant Other Observable Inputs [Member]
CLO notes	0	0
CLO Notes [Member] | Significant Unobservable Inputs [Member]
CLO notes	$ (3,855.0)	$ (5,512.9)