Consolidated Investment Products (Beginning And Ending Fair Value Measurements For Level 3 Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance (Asset)	$ 16.2	$ 0
Purchases (Asset)	9.0	2.5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(1.0)	0
Gains and losses included in the Consolidated Statement of Income (Asset)	(6.0)	(0.5)
Ending balance (Asset)	30.2	16.2
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net unrealized gains/losses attributable to investments	60.2	(9.6)
Level 3 Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance (Asset)	500.9	602.9
Purchases (Asset)	302.3	31.5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(138.7)	(148.0)
Issuances (Asset)	1.8	3.8
Settlements (Asset)	0	0
Deconsolidation of CIP	0	(18.4)
Gains and losses included in the Consolidated Statement of Income (Asset)	107.6	35.7
Transfers to Level 2	0	(6.1)
Foreign exchange (Asset)	0	(0.5)
Ending balance (Asset)	773.9	500.9
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deconsolidation of CIP	0	(18.4)
Transfers to Level 2	0	(6.1)
Level 3 Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deconsolidation of CIP	339.0	239.5
Transfers to Level 2	0	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance (Liability)	(4,181.7)	(3,899.4)
Purchases (Liability)	0	0
Sales (Liability)	0	0
Issuances (Liability)	(1,995.5)	(1,323.9)
Settlements (Liability)	706.8	850.4
Deconsolidation of CIP	339.0	239.5
Gains and losses included in the Consolidated Statements of Income (Liability)	(18.2)	(44.3)
Transfers to Level 2	0	0
Foreign exchange (Liability)	0	(4.0)
Ending balance (Liability)	$ (5,149.6)	$ (4,181.7)