Consolidated Investment Products (Beginning And Ending Fair Value Measurements For Level 3 Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	9 Months Ended	3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended
	Sep. 30, 2012	Jun. 30, 2011	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2012 Level 3 Assets [Member]		Sep. 30, 2011 Level 3 Assets [Member]		Sep. 30, 2012 Level 3 Assets [Member]		Sep. 30, 2011 Level 3 Assets [Member]		Sep. 30, 2012 Level 3 Liabilities [Member]		Sep. 30, 2011 Level 3 Liabilities [Member]		Sep. 30, 2012 Level 3 Liabilities [Member]		Sep. 30, 2011 Level 3 Liabilities [Member]
Beginning balance (Asset)					$ 854.6		$ 909.8		$ 929.1		$ 972.8
Beginning Balance (Liability)													(5,069.7)		(6,292.7)		(5,512.9)		(5,865.4)
Purchases, Assets					6.2		6.1		6.7		33.0
Purchases, Liabilities													0		0		0		0
Sales, Assets					(92.3)		(26.2)		(148.0)		(157.7)
Sales, Liabilities													0		0		0		0
Issuances, Assets					0				0
Issuances, Liabilities													(433.1)				(758.4)
Settlements, Assets					0		0		0		0
Settlements, Liabilities													354.7		190.3		550.5		450.3
deconsolidation of consolidated investment products level three					0				0				1,550.3				2,123.7
Gain and losses included in the Condensed Consolidated Statement of Income, Level 3 Assets					23.3	[1]	35.1	[1]	14.5	[1]	82.5	[1]
Gain and losses included in the Condensed Consolidated Statement of Income, Level 3 Liabilities													(121.2)	[1]	249.0	[1]	(279.9)	[1]	(184.7)	[1]
Foreign exchange, Assets					4.8		6.3		(5.7)		0.5
Foreign exchange, Liabilities													(136.0)		(12.9)		(22.0)		(266.5)
Ending balance (Asset)					796.6		931.1		796.6		931.1
Ending Balance (Liability)													(3,855.0)		(5,866.3)		(3,855.0)		(5,866.3)
Net unrealized gains/losses attributable to investments	$ 42.6	$ 26.5	$ 37.5	$ 39.5

[1] Included in gains and losses of consolidated investment products in the Condensed Consolidated Statement of Income for the three and nine months ended September 30, 2012 are $42.6 million in net unrealized gains and $39.5 million in net unrealized gains attributable to investments still held at September 30, 2012 by consolidated investment products (three and nine months ended September 30, 2011: $26.5 million in net unrealized gains and $37.5 million in net unrealized gains attributable to investments still held at September 30, 2011).