Investments (Mortgage Loans and Valuation Allowance by Portfolio Segment) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	$ 122,000,000	$ 237,000,000
Recorded Investment	120,000,000	231,000,000
Valuation Allowances	26,000,000	56,000,000
Unpaid Principal Balance	138,000,000	287,000,000
Recorded Investment	134,000,000	284,000,000
Recorded Investment	48,755,000,000	45,440,000,000
Valuation Allowances	232,000,000	216,000,000
Carrying Value	228,000,000	459,000,000
Average Recorded Investment	391,000,000	583,000,000
Commercial
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	75,000,000	173,000,000
Recorded Investment	75,000,000	169,000,000
Valuation Allowances	24,000,000	49,000,000
Unpaid Principal Balance	84,000,000	247,000,000
Recorded Investment	84,000,000	246,000,000
Recorded Investment	32,323,000,000	32,657,000,000
Valuation Allowances	158,000,000	164,000,000
Carrying Value	135,000,000	366,000,000
Average Recorded Investment	298,000,000	430,000,000
Agricultural
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	47,000,000	64,000,000
Recorded Investment	45,000,000	62,000,000
Valuation Allowances	2,000,000	7,000,000
Unpaid Principal Balance	14,000,000	35,000,000
Recorded Investment	13,000,000	34,000,000
Recorded Investment	10,975,000,000	10,929,000,000
Valuation Allowances	33,000,000	33,000,000
Carrying Value	56,000,000	89,000,000
Average Recorded Investment	76,000,000	151,000,000
Residential
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Valuation Allowances	0	0
Unpaid Principal Balance	40,000,000	5,000,000
Recorded Investment	37,000,000	4,000,000
Recorded Investment	5,457,000,000	1,854,000,000
Valuation Allowances	41,000,000	19,000,000
Carrying Value	37,000,000	4,000,000
Average Recorded Investment	$ 17,000,000	$ 2,000,000

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

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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

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