Consolidated Investment Products (Condensed Consolidating Balance Sheet Line Items Reflecting Impact Of Consolidation Of Investment Products Into The Condensed Consolidated Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets	$ 3,907.6	$ 3,834.1
Non-current assets	13,584.8	15,512.9
Total assets	17,492.4	19,347.0
Current liabilities	2,713.0	2,974.4
Long-term debt of consolidated investment products	3,899.4	5,512.9
Other non-current liabilities	1,831.0	1,722.1
Total liabilities	(8,443.4)	(10,209.4)
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	128.8	334.3
Other equity attributable to common shareholders	8,188.0	7,784.8
Equity attributable to noncontrolling interests in consolidated entities	732.2	1,018.5
Total liabilities and equity	17,492.4	19,347.0
CLOs - VIEs [Member]
Current assets	266.4	394.5
Non-current assets	3,948.0	5,682.3
Total assets	4,214.4	6,076.8
Current liabilities	105.3	179.2
Long-term debt of consolidated investment products	3,980.7	5,563.3
Other non-current liabilities	0	0
Total liabilities	(4,086.0)	(5,742.5)
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	128.8	334.3
Other equity attributable to common shareholders	(0.4)	0
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total liabilities and equity	4,214.4	6,076.8
Other VIEs [Member]
Current assets	0.4	3.1
Non-current assets	35.9	42.8
Total assets	36.3	45.9
Current liabilities	0.5	0.4
Long-term debt of consolidated investment products	0	0
Other non-current liabilities	0	0
Total liabilities	(0.5)	(0.4)
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	0	0
Other equity attributable to common shareholders	(0.1)	0.1
Equity attributable to noncontrolling interests in consolidated entities	35.9	45.4
Total liabilities and equity	36.3	45.9
VOEs [Member]
Current assets	120.9	113.7
Non-current assets	607.9	903.8
Total assets	728.8	1,017.5
Current liabilities	2.9	5.8
Long-term debt of consolidated investment products	0	0
Other non-current liabilities	0	0
Total liabilities	(2.9)	(5.8)
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	0	0
Other equity attributable to common shareholders	34.0	43.1
Equity attributable to noncontrolling interests in consolidated entities	691.9	968.6
Total liabilities and equity	728.8	1,017.5
VIE Adjustments [Member]
Current assets	(20.2)	(29.9)
Non-current assets	(107.9)	(92.5)
Total assets	(128.1)	(122.4)
Current liabilities	(13.3)	(29.9)
Long-term debt of consolidated investment products	(81.3)	(50.4)
Other non-current liabilities	0	0
Total liabilities	94.6	80.3
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	0	0
Other equity attributable to common shareholders	(33.5)	(42.1)
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total liabilities and equity	(128.1)	(122.4)
Consolidated Investment Products [Member]
Current assets	367.5	481.4
Non-current assets	4,483.9	6,536.4
Total assets	4,851.4	7,017.8
Current liabilities	95.4	155.5
Long-term debt of consolidated investment products	3,899.4	5,512.9
Other non-current liabilities	0	0
Total liabilities	(3,994.8)	(5,668.4)
Retained earnings accumulated deficit appropriated for investors in consolidated investment products	128.8	334.3
Other equity attributable to common shareholders	0	1.1
Equity attributable to noncontrolling interests in consolidated entities	727.8	1,014.0
Total liabilities and equity	$ 4,851.4	$ 7,017.8