Commitments and Contingencies Level 4 (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Mar. 31, 2017
Derivative Commitments [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value		$ 826
Collateral Already Posted, Aggregate Fair Value		866
Reinsurance Recoverables, Including Reinsurance Premium Paid	$ 23,311	23,405
GMWB Product Derivatives [Member]
Derivative Commitments [Line Items]
Collateral Already Posted, Aggregate Fair Value		31
Premium [Member]
Derivative Commitments [Line Items]
Payments for Reinsurance	650
Asbestos and Environmental [Member]
Derivative Commitments [Line Items]
Reinsurance Recoverables, Including Reinsurance Premium Paid	1,500
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	$ 1,700
Cash and Cash Equivalents [Member]
Derivative Commitments [Line Items]
Collateral Already Posted, Aggregate Fair Value		$ 0

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624258-113959

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The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624258-113959

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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.

+ References

No definition available.

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- Definition

Cash payments made for reinsurance during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585

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Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21409-158489

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),6)
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Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts for accident years not separately presented in claim development information. Excludes unallocated claim adjustment expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=65670685&loc=SL65671311-158438

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