Derivative Instruments - Derivatives - Derivative Balance Sheet Classification (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Notional Amount	$ 12,361	$ 12,291
Fair Value	(60)	(61)
Asset Derivatives	30	31
Liability Derivatives	(90)	(92)
Fixed maturities, available-for-sale
Derivatives, Fair Value [Line Items]
Notional Amount	153	153
Fair Value	0	0
Asset Derivatives	0	0
Liability Derivatives	0	0
Other investments
Derivatives, Fair Value [Line Items]
Notional Amount	1,353	9,864
Fair Value	11	7
Asset Derivatives	12	23
Liability Derivatives	(1)	(16)
Other liabilities
Derivatives, Fair Value [Line Items]
Notional Amount	10,855	2,274
Fair Value	(71)	(68)
Asset Derivatives	18	8
Liability Derivatives	(89)	(76)
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	10,101	10,098
Fair Value	(57)	(56)
Asset Derivatives	26	27
Liability Derivatives	(83)	(83)
Interest rate swaps \| Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	2,040	2,040
Fair Value	0	1
Asset Derivatives	0	2
Liability Derivatives	0	(1)
Interest rate swaps \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	7,600	7,100
Foreign currency swaps \| Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	220	153
Fair Value	(3)	(6)
Asset Derivatives	4	2
Liability Derivatives	(7)	(8)
Total cash flow hedges
Derivatives, Fair Value [Line Items]
Notional Amount	2,260	2,193
Fair Value	(3)	(5)
Asset Derivatives	4	4
Liability Derivatives	(7)	(9)
Interest rate swaps and futures \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	8,338	8,451
Fair Value	(62)	(62)
Asset Derivatives	3	8
Liability Derivatives	(65)	(70)
Foreign currency swaps and forwards \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	389	287
Fair Value	(2)	(1)
Asset Derivatives	0	0
Liability Derivatives	(2)	(1)
Credit derivatives that purchase credit protection \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	115	6
Fair Value	(1)	0
Asset Derivatives	0	0
Liability Derivatives	(1)	0
Credit derivatives that assume credit risk \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	514	1,102
Fair Value	11	3
Asset Derivatives	11	8
Liability Derivatives	0	(5)
Credit derivatives in offsetting positions \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	35	41
Fair Value	0	0
Asset Derivatives	6	6
Liability Derivatives	(6)	(6)
Equity index swaps and options \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional Amount	710	211
Fair Value	(3)	4
Asset Derivatives	6	5
Liability Derivatives	$ (9)	$ (1)

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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-SubTopic 20
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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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