Consolidated Investment Products (VIE Balance Sheets Consolidated In Period) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Current assets	$ 3,673.0	$ 3,834.1
Non-current assets	14,939.9	15,512.9
Total assets	18,612.9	19,347.0
Current liabilities	2,724.7	2,974.4
Non-current liabilities	6,769.4	7,235.0
Total liabilities	9,494.1	10,209.4
Total equity	9,118.8	9,137.6	9,197.8	9,360.9
Total liabilities and equity	18,612.9	19,347.0
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member]
Current assets	48.2
Non-current assets	594.1
Total assets	642.3
Current liabilities	18.7
Non-current liabilities	576.0
Total liabilities	594.7
Total equity	47.6
Total liabilities and equity	642.3
CLOs - VIEs [Member]
Current assets	410.5	394.5
Non-current assets	5,163.9	5,682.3
Total assets	5,574.4	6,076.8
Current liabilities	189.3	179.2
Total liabilities	5,322.6	5,742.5
Total liabilities and equity	5,574.4	6,076.8
New CLO [Member] | CLOs - VIEs [Member]
Current assets	174.8
Non-current assets	325.6
Total assets	500.4
Current liabilities	155.7
Non-current liabilities	345.3
Total liabilities	501.0
Total equity	(0.6)
Total liabilities and equity	$ 500.4