Guarantor Condensed Consolidating Financial Statements (Condensed Consolidating Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 718.4	$ 727.4	$ 621.5	$ 740.5
Cash and cash equivalents of consolidated investment products	380.5	382.3
Unsettled fund receivables	487.1	444.4
Accounts receivable	398.4	424.4
Accounts receivable of consolidated investment products	114.7	98.5
Investments	344.5	283.7
Prepaid assets	51.4	51.2
Other current assets	88.4	150.0
Deferred tax asset, net	24.2	28.7
Assets held for policyholders	1,065.4	1,243.5
Total current assets	3,673.0	3,834.1
Non-current assets:
Investments	218.8	200.8
Investments of consolidated investment products	6,050.9	6,629.0
Security deposit assets and receivables	75.0	81.2
Other non-current assets	18.4	17.9
Deferred sales commissions	43.8	40.5
Property and equipment, net	314.6	312.8
Intangible assets, net	1,302.3	1,322.8
Goodwill	6,916.1	6,907.9
Total non-current assets	14,939.9	15,512.9
Total assets	18,612.9	19,347.0
Current liabilities:
Current maturities of total debt	333.5	215.1
Unsettled fund payables	472.7	439.6
Income taxes payable	50.1	59.6
Other current liabilities	616.0	841.5
Other current liabilities of consolidated investment products	187.0	175.1
Policyholder payables	1,065.4	1,243.5
Total current liabilities	2,724.7	2,974.4
Non-current liabilities:
Long-term debt	1,008.1	1,069.6
Long-term debt of consolidated investment products	5,069.7	5,512.9
Deferred tax liabilities, net	307.8	274.0
Security deposits payable	75.0	81.2
Other non-current liabilities	308.8	297.3
Total non-current liabilities	6,769.4	7,235.0
Total liabilities	9,494.1	10,209.4
Equity:
Total equity attributable to common shareholders	8,165.8	8,119.1
Equity attributable to noncontrolling interests in consolidated entities	953.0	1,018.5
Total equity	9,118.8	9,137.6	9,197.8	9,360.9
Total liabilities and equity	18,612.9	19,347.0
Guarantors [Member]
Current assets:
Cash and cash equivalents	12.6	20.6	15.3	12.4
Cash and cash equivalents of consolidated investment products	0	0
Unsettled fund receivables	0	0
Accounts receivable	152.3	163.6
Accounts receivable of consolidated investment products	0	0
Investments	4.1	4.2
Prepaid assets	11.8	9.7
Other current assets	51.0	39.3
Deferred tax asset, net	17.5	18.9
Assets held for policyholders	0	0
Intercompany Receivable - Short Term	16.5	37.9
Total current assets	265.8	294.2
Non-current assets:
Investments	55.1	50.0
Investments of consolidated investment products	0	0
Security deposit assets and receivables	0	0
Other non-current assets	10.0	8.5
Deferred sales commissions	10.0	13.9
Property and equipment, net	138.7	145.3
Intangible assets, net	1,192.2	420.6
Goodwill	2,583.5	2,312.8
Deferred tax assets, net	0	0
Intercompany Loans Receivable - Non-Current	564.8	772.1
Investments In Subsidiaries	458.2	1,228.2
Total non-current assets	5,012.5	4,951.4
Total assets	5,278.3	5,245.6
Current liabilities:
Current maturities of total debt	0	0
Unsettled fund payables	0	0
Income taxes payable	0	0
Other current liabilities	124.7	144.3
Other current liabilities of consolidated investment products	0	0
Policyholder payables	0	0
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	0	0
Total current liabilities	124.7	144.3
Non-current liabilities:
Long-term debt	589.0	539.0
Long-term debt of consolidated investment products	0	0
Deferred tax liabilities, net	337.9	29.6
Security deposits payable	0	0
Other non-current liabilities	56.1	55.1
Intercompany Payable - Non-Current	1,774.2	1,728.3
Total non-current liabilities	2,757.2	2,352.0
Total liabilities	2,881.9	2,496.3
Equity:
Total equity attributable to common shareholders	2,396.4	2,749.3
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total equity	2,396.4	2,749.3
Total liabilities and equity	5,278.3	5,245.6
Non-Guarantors [Member]
Current assets:
Cash and cash equivalents	703.3	703.0	602.5	725.9
Cash and cash equivalents of consolidated investment products	380.5	382.3
Unsettled fund receivables	487.1	444.4
Accounts receivable	246.1	260.8
Accounts receivable of consolidated investment products	114.7	98.5
Investments	338.8	266.2
Prepaid assets	39.4	41.5
Other current assets	56.3	120.5
Deferred tax asset, net	6.7	9.8
Assets held for policyholders	1,065.4	1,243.5
Intercompany Receivable - Short Term	38.3	38.0
Total current assets	3,476.6	3,608.5
Non-current assets:
Investments	152.6	144.4
Investments of consolidated investment products	6,050.9	6,629.0
Security deposit assets and receivables	75.0	81.2
Other non-current assets	5.5	6.6
Deferred sales commissions	33.8	26.6
Property and equipment, net	175.9	167.5
Intangible assets, net	110.1	902.2
Goodwill	3,900.0	4,161.8
Deferred tax assets, net	30.1	0
Intercompany Loans Receivable - Non-Current	1,791.4	1,834.0
Investments In Subsidiaries	276.7	5.6
Total non-current assets	12,602.0	13,958.9
Total assets	16,078.6	17,567.4
Current liabilities:
Current maturities of total debt	0	0
Unsettled fund payables	472.7	439.6
Income taxes payable	61.8	63.1
Other current liabilities	481.9	685.4
Other current liabilities of consolidated investment products	187.0	175.1
Policyholder payables	1,065.4	1,243.5
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	42.3	62.8
Total current liabilities	2,311.1	2,669.5
Non-current liabilities:
Long-term debt	0	0
Long-term debt of consolidated investment products	5,069.7	5,512.9
Deferred tax liabilities, net	0	244.4
Security deposits payable	75.0	81.2
Other non-current liabilities	252.7	242.2
Intercompany Payable - Non-Current	604.4	444.8
Total non-current liabilities	6,001.8	6,525.5
Total liabilities	8,312.9	9,195.0
Equity:
Total equity attributable to common shareholders	6,812.7	7,353.9
Equity attributable to noncontrolling interests in consolidated entities	953.0	1,018.5
Total equity	7,765.7	8,372.4
Total liabilities and equity	16,078.6	17,567.4
Issuer [Member]
Current assets:
Cash and cash equivalents	2.4	3.1	0.3	1.1
Cash and cash equivalents of consolidated investment products	0	0
Unsettled fund receivables	0	0
Accounts receivable	0	0
Accounts receivable of consolidated investment products	0	0
Investments	0	0
Prepaid assets	0	0
Other current assets	2.1	1.1
Deferred tax asset, net	0	0
Assets held for policyholders	0	0
Intercompany Receivable - Short Term	328.9	29.0
Total current assets	333.4	33.2
Non-current assets:
Investments	7.9	3.4
Investments of consolidated investment products	0	0
Security deposit assets and receivables	0	0
Other non-current assets	2.9	2.8
Deferred sales commissions	0	0
Property and equipment, net	0	0
Intangible assets, net	0	0
Goodwill	432.6	433.3
Deferred tax assets, net	0	0
Intercompany Loans Receivable - Non-Current	607.4	573.5
Investments In Subsidiaries	5,143.4	5,116.3
Total non-current assets	6,194.2	6,129.3
Total assets	6,527.6	6,162.5
Current liabilities:
Current maturities of total debt	333.5	215.1
Unsettled fund payables	0	0
Income taxes payable	9.3	7.4
Other current liabilities	8.7	11.1
Other current liabilities of consolidated investment products	0	0
Policyholder payables	0	0
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	4.1	29.9
Total current liabilities	355.6	263.5
Non-current liabilities:
Long-term debt	419.1	530.6
Long-term debt of consolidated investment products	0	0
Deferred tax liabilities, net	0	0
Security deposits payable	0	0
Other non-current liabilities	0	0
Intercompany Payable - Non-Current	568.1	656.5
Total non-current liabilities	987.2	1,187.1
Total liabilities	1,342.8	1,450.6
Equity:
Total equity attributable to common shareholders	5,184.8	4,711.9
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total equity	5,184.8	4,711.9
Total liabilities and equity	6,527.6	6,162.5
Parent Company [Member]
Current assets:
Cash and cash equivalents	0.1	0.7	3.4	1.1
Cash and cash equivalents of consolidated investment products	0	0
Unsettled fund receivables	0	0
Accounts receivable	0	0
Accounts receivable of consolidated investment products	0	0
Investments	1.6	13.3
Prepaid assets	0.2	0
Other current assets	0	0
Deferred tax asset, net	0	0
Assets held for policyholders	0	0
Intercompany Receivable - Short Term	0	0
Total current assets	1.9	14.0
Non-current assets:
Investments	3.2	3.0
Investments of consolidated investment products	0	0
Security deposit assets and receivables	0	0
Other non-current assets	0	0
Deferred sales commissions	0	0
Property and equipment, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Deferred tax assets, net	0	0
Intercompany Loans Receivable - Non-Current	0	0
Investments In Subsidiaries	8,515.6	8,465.0
Total non-current assets	8,518.8	8,468.0
Total assets	8,520.7	8,482.0
Current liabilities:
Current maturities of total debt	0	0
Unsettled fund payables	0	0
Income taxes payable	0	0
Other current liabilities	0.7	0.7
Other current liabilities of consolidated investment products	0	0
Policyholder payables	0	0
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	337.3	12.2
Total current liabilities	338.0	12.9
Non-current liabilities:
Long-term debt	0	0
Long-term debt of consolidated investment products	0	0
Deferred tax liabilities, net	0	0
Security deposits payable	0	0
Other non-current liabilities	0	0
Intercompany Payable - Non-Current	16.9	350.0
Total non-current liabilities	16.9	350.0
Total liabilities	354.9	362.9
Equity:
Total equity attributable to common shareholders	8,165.8	8,119.1
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total equity	8,165.8	8,119.1
Total liabilities and equity	8,520.7	8,482.0
Adjustments [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Cash and cash equivalents of consolidated investment products	0	0
Unsettled fund receivables	0	0
Accounts receivable	0	0
Accounts receivable of consolidated investment products	0	0
Investments	0	0
Prepaid assets	0	0
Other current assets	(21.0)	(10.9)
Deferred tax asset, net	0	0
Assets held for policyholders	0	0
Intercompany Receivable - Short Term	(383.7)	(104.9)
Total current assets	(404.7)	(115.8)
Non-current assets:
Investments	0	0
Investments of consolidated investment products	0	0
Security deposit assets and receivables	0	0
Other non-current assets	0	0
Deferred sales commissions	0	0
Property and equipment, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Deferred tax assets, net	(30.1)	0
Intercompany Loans Receivable - Non-Current	(2,963.6)	(3,179.6)
Investments In Subsidiaries	(14,393.9)	(14,815.1)
Total non-current assets	(17,387.6)	(17,994.7)
Total assets	(17,792.3)	(18,110.5)
Current liabilities:
Current maturities of total debt	0	0
Unsettled fund payables	0	0
Income taxes payable	(21.0)	(10.9)
Other current liabilities	0	0
Other current liabilities of consolidated investment products	0	0
Policyholder payables	0	0
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	(383.7)	(104.9)
Total current liabilities	(404.7)	(115.8)
Non-current liabilities:
Long-term debt	0	0
Long-term debt of consolidated investment products	0	0
Deferred tax liabilities, net	(30.1)	0
Security deposits payable	0	0
Other non-current liabilities	0	0
Intercompany Payable - Non-Current	(2,963.6)	(3,179.6)
Total non-current liabilities	(2,993.7)	(3,179.6)
Total liabilities	(3,398.4)	(3,295.4)
Equity:
Total equity attributable to common shareholders	(14,393.9)	(14,815.1)
Equity attributable to noncontrolling interests in consolidated entities	0	0
Total equity	(14,393.9)	(14,815.1)
Total liabilities and equity	(17,792.3)	(18,110.5)
Consolidated [Member]
Current assets:
Cash and cash equivalents	718.4	727.4	621.5	740.5
Cash and cash equivalents of consolidated investment products	380.5	382.3
Unsettled fund receivables	487.1	444.4
Accounts receivable	398.4	424.4
Accounts receivable of consolidated investment products	114.7	98.5
Investments	344.5	283.7
Prepaid assets	51.4	51.2
Other current assets	88.4	150.0
Deferred tax asset, net	24.2	28.7
Assets held for policyholders	1,065.4	1,243.5
Intercompany Receivable - Short Term	0	0
Total current assets	3,673.0	3,834.1
Non-current assets:
Investments	218.8	200.8
Investments of consolidated investment products	6,050.9	6,629.0
Security deposit assets and receivables	75.0	81.2
Other non-current assets	18.4	17.9
Deferred sales commissions	43.8	40.5
Property and equipment, net	314.6	312.8
Intangible assets, net	1,302.3	1,322.8
Goodwill	6,916.1	6,907.9
Deferred tax assets, net	0	0
Intercompany Loans Receivable - Non-Current	0	0
Investments In Subsidiaries	0	0
Total non-current assets	14,939.9	15,512.9
Total assets	18,612.9	19,347.0
Current liabilities:
Current maturities of total debt	333.5	215.1
Unsettled fund payables	472.7	439.6
Income taxes payable	50.1	59.6
Other current liabilities	616.0	841.5
Other current liabilities of consolidated investment products	187.0	175.1
Policyholder payables	1,065.4	1,243.5
Deferred Tax Liabilities	0	0
Intercompany Payables - Short Term	0	0
Total current liabilities	2,724.7	2,974.4
Non-current liabilities:
Long-term debt	1,008.1	1,069.6
Long-term debt of consolidated investment products	5,069.7	5,512.9
Deferred tax liabilities, net	307.8	274.0
Security deposits payable	75.0	81.2
Other non-current liabilities	308.8	297.3
Intercompany Payable - Non-Current	0	0
Total non-current liabilities	6,769.4	7,235.0
Total liabilities	9,494.1	10,209.4
Equity:
Total equity attributable to common shareholders	8,165.8	8,119.1
Equity attributable to noncontrolling interests in consolidated entities	953.0	1,018.5
Total equity	9,118.8	9,137.6
Total liabilities and equity	$ 18,612.9	$ 19,347.0