Consolidated Investment Products (Fair Value Hierarchy Levels Of Investments Held And Notes Issued By Consolidated Investment Products) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Real Estate Investments, Net	$ 23.9
Investments Of Consolidated Investment Products	4,036.9	$ 6,016.1
Fair Value, Inputs, Level 1 [Member]
Real Estate Investments, Net	0.0
Investments Of Consolidated Investment Products	115.4	7.7
Significant Other Observable Inputs (Level 2) [Member]
Real Estate Investments, Net	0.0
Investments Of Consolidated Investment Products	3,841.7	5,251.6
Significant Unobservable Inputs (Level 3) [Member]
Real Estate Investments, Net	23.9
Investments Of Consolidated Investment Products	23.9	388.6
Bank Loans [Member]
CLO Collateral Assets	3,485.3	5,179.6
Bank Loans [Member] | Fair Value, Inputs, Level 1 [Member]
CLO Collateral Assets	0.0	0.0
Bank Loans [Member] | Significant Other Observable Inputs (Level 2) [Member]
CLO Collateral Assets	3,485.3	5,179.6
Bank Loans [Member] | Significant Unobservable Inputs (Level 3) [Member]
CLO Collateral Assets	0.0	0.0
Bonds [Member]
CLO Collateral Assets	354.7	71.1
Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
CLO Collateral Assets	0.0	0.0
Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
CLO Collateral Assets	354.7	71.1
Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member]
CLO Collateral Assets	0.0	0.0
Equity Securities [Member]
CLO Collateral Assets	67.9	0.9
Private Equity Fund Assets	49.2	364.6
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
CLO Collateral Assets	66.2	0.0
Private Equity Fund Assets	49.2	7.7
Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
CLO Collateral Assets	1.7	0.9
Private Equity Fund Assets	0.0	0.0
Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
CLO Collateral Assets	0.0	0.0
Private Equity Fund Assets	0.0	356.9
Private Equity Funds [Member]
Private Equity Fund Assets	55.9	368.2
Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Private Equity Fund Assets	0.0	0.0
Private Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Private Equity Fund Assets	0.0	0.0
Private Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Private Equity Fund Assets	0.0	0.0
Investments Measured at NAV [Member]
Real Estate Investments, Net	0.0
Investments Of Consolidated Investment Products	55.9	368.2
Investments Measured at NAV [Member] | Bank Loans [Member]
CLO Collateral Assets	0.0	0.0
Investments Measured at NAV [Member] | Bonds [Member]
CLO Collateral Assets	0.0	0.0
Investments Measured at NAV [Member] | Equity Securities [Member]
CLO Collateral Assets	0.0	0.0
Private Equity Fund Assets	0.0	0.0
Investments Measured at NAV [Member] | Debt Securities [Member]
Private Equity Fund Assets		0.0
Investments Measured at NAV [Member] | Private Equity Funds [Member]
Private Equity Fund Assets	$ 55.9	$ 368.2