Investments (Valuation Allowance Rollforward by Portfolio Segment) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	$ 272	$ 304	$ 393
Provision (release)	(15)us-gaap_ProvisionForLoanAndLeaseLosses	21us-gaap_ProvisionForLoanAndLeaseLosses	48us-gaap_ProvisionForLoanAndLeaseLosses
Charge-offs, net of recoveries	29	11	36
Transfers to held-for-sale	0	0	(5)
Ending Balance	258	272	304
Commercial
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	213	256	318
Provision (release)	8	43	50
Charge-offs, net of recoveries	23	0	12
Transfers to held-for-sale	0	0	0
Ending Balance	182	213	256
Agricultural
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	40	48	75
Provision (release)	4	(3)	(2)
Charge-offs, net of recoveries	1	11	24
Transfers to held-for-sale	0	0	(5)
Ending Balance	35	40	48
Residential
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	19	0	0
Provision (release)	(27)	(19)	0
Charge-offs, net of recoveries	5	0	0
Transfers to held-for-sale	0	0	0
Ending Balance	$ 41	$ 19	$ 0

Amount of other addition (reduction) in allowance reserve for credit loss.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

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The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Amount of expense related to estimated loss from loan and lease transactions.

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