Investments (Mortgage Loans and Valuation Allowance by Portfolio Segment) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	$ 192	$ 49
Recorded Investment	170	47
Valuation Allowances	144	3
Unpaid Principal Balance	256	220
Recorded Investment	239	209
Recorded Investment	68,849	66,678
Valuation Allowances	323	315
Carrying Value	265	253
Commercial
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	176	0
Recorded Investment	157	0
Valuation Allowances	143	0
Unpaid Principal Balance	12	57
Recorded Investment	12	57
Recorded Investment	44,996	43,955
Valuation Allowances	224	217
Carrying Value	26	57
Agricultural
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	16	49
Recorded Investment	13	47
Valuation Allowances	1	3
Unpaid Principal Balance	39	22
Recorded Investment	38	21
Recorded Investment	13,383	13,120
Valuation Allowances	40	39
Carrying Value	50	65
Residential
Mortgage Loans on Real Estate [Line Items]
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Valuation Allowances	0	0
Unpaid Principal Balance	205	141
Recorded Investment	189	131
Recorded Investment	10,470	9,603
Valuation Allowances	59	59
Carrying Value	$ 189	$ 131

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=66008989&loc=SL6953423-111524

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The balance of financing receivables that were collectively evaluated for impairment.

+ References

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)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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+ 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=66008989&loc=SL6953550-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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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