Derivative Financial Instruments (Details 1) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Derivative Financial Instruments, exposure
Cash and securities posted under collateral arrangements associated with derivative credit support agreements	$ 373.2	$ 376.8
Aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position	1,245.7	1,262.0
Collateral posted supporting derivatives with credit-risk-related contingent features that were in a liability position	373.2	376.8
Additional collateral required to be posted if derivative credit-risk-related contingent features were triggered	53.8
Cash collateral received associated with derivative credit support annex agreements	201.0	249.2
Notional amount	31,378.9	31,531.3
Gross credit exposure	1,073.6	1,177.0
Less: collateral received	201.0	249.2
Net credit exposure	872.6	927.8
Interest rate swaps
Derivative Financial Instruments, exposure
Notional amount	19,249.8	19,803.0
Gross credit exposure	566.7	607.1
Interest rate collars
Derivative Financial Instruments, exposure
Notional amount	500.0	500.0
Gross credit exposure	2.5	1.7
Interest rate futures
Derivative Financial Instruments, exposure
Notional amount	216.9	0.8
Swaptions
Derivative Financial Instruments, exposure
Notional amount	68.5	68.5
Gross credit exposure		0.1
Foreign currency swaps
Derivative Financial Instruments, exposure
Notional amount	4,027.7	4,615.2
Gross credit exposure	432.3	493.2
Currency forwards
Derivative Financial Instruments, exposure
Notional amount	70.7	72.3
Gross credit exposure	2.6	3.3
Equity options
Derivative Financial Instruments, exposure
Notional amount	1,208.8	997.5
Gross credit exposure	63.2	64.9
Equity futures
Derivative Financial Instruments, exposure
Notional amount	169.5
Credit default swaps
Derivative Financial Instruments, exposure
Notional amount	1,530.2	1,482.4
Gross credit exposure	6.3	6.7
Embedded derivative financial instruments
Derivative Financial Instruments, exposure
Notional amount	$ 4,336.8	$ 3,991.6

The carrying value as of the balance sheet date of the cash received as collateral associated with derivative credit support annex agreements.

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The carrying value as of the balance sheet date of the cash and securities pledged as collateral associated with derivative credit support agreements.

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The carrying value as of the balance sheet date of the cash and securities received as collateral associated with derivative credit support agreements.

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- Definition

The amount at risk if a counterparty to the derivative instruments does not perform.

+ Details

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- Definition

The amount at risk if a counterparty to the derivative instrument does not perform, after considering collateral received.

+ Details

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- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44D
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44D
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44D
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

Aggregate notional amount of all derivatives. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

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