Investments (Impaired Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Impaired Mortgage Loans
Unpaid Principal Balance	$ 187		$ 187		$ 294
Recorded Investment	185		185		288
Valuation allowances	39		39		66
Carrying Value	460		460		556
Unpaid Principal Balance	320		320		339
Recorded Investment	314		314		334
Unpaid Principal Balance	507		507		633
Average Recorded Investment	559	703	580	713
Interest Income	7	6	13	10
Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	146		146		222
Commercial mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	132		132		214
Recorded Investment	132		132		210
Valuation allowances	33		33		58
Carrying Value	382		382		448
Unpaid Principal Balance	285		285		299
Recorded Investment	283		283		296
Unpaid Principal Balance	417		417		513
Average Recorded Investment	462	531	476	534
Interest Income	4	4	7	7
Commercial mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	99		99		152
Agricultural [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	55		55		68
Recorded Investment	53		53		66
Valuation allowances	6		6		7
Carrying Value	69		69		93
Unpaid Principal Balance	23		23		35
Recorded Investment	22		22		34
Unpaid Principal Balance	78		78		103
Average Recorded Investment	88	158	92	165
Interest Income	3	2	6	3
Agricultural [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	47		47		59
Residential [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	0		0		12
Recorded Investment	0		0		12
Valuation allowances	0		0		1
Carrying Value	9		9		15
Unpaid Principal Balance	12		12		5
Recorded Investment	9		9		4
Unpaid Principal Balance	12		12		17
Average Recorded Investment	9	14	12	14
Interest Income	0	0	0	0
Residential [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	$ 0		$ 0		$ 11

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

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- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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