Investments (Impaired Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Impaired Mortgage Loans
Unpaid Principal Balance	$ 135		$ 135		$ 294
Recorded Investment	132		132		288
Valuation allowances	26		26		66
Carrying Value	249		249		556
Unpaid Principal Balance	147		147		339
Recorded Investment	143		143		334
Unpaid Principal Balance	282		282		633
Average Recorded Investment	388	704	504	711
Interest Income	2	9	15	19
Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	106		106		222
Commercial mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	85		85		214
Recorded Investment	85		85		210
Valuation allowances	24		24		58
Carrying Value	165		165		448
Unpaid Principal Balance	105		105		299
Recorded Investment	104		104		296
Unpaid Principal Balance	190		190		513
Average Recorded Investment	302	525	405	530
Interest Income	0	4	7	11
Commercial mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	61		61		152
Agricultural [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	50		50		68
Recorded Investment	47		47		66
Valuation allowances	2		2		7
Carrying Value	60		60		93
Unpaid Principal Balance	16		16		35
Recorded Investment	15		15		34
Unpaid Principal Balance	66		66		103
Average Recorded Investment	69	165	84	167
Interest Income	1	5	7	8
Agricultural [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Carrying Value	45		45		59
Residential [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	0		0		12
Recorded Investment	0		0		12
Valuation allowances	0		0		1
Carrying Value	24		24		15
Unpaid Principal Balance	26		26		5
Recorded Investment	24		24		4
Unpaid Principal Balance	26		26		17
Average Recorded Investment	17	14	15	14
Interest Income	1	0	1	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

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+ 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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