Fair Value of Assets and Liabilities - Rollforward of level 3 assets and liabilities held at fair value on a recurring basis during the period (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	$ 738	$ 697
Total gains (losses) included in: net income	(29)	26
Total gains (losses) included in: OCI	(2)	4
Transfers into Level 3	26	18
Transfers out of Level 3	(74)	(47)
Purchases	60	116
Sales	(11)	(93)
Issues	0	0
Settlements	(31)	(7)
Balance at end of period	677	714
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Calculation
Balance at the beginning of the period	(462)	(224)
Total gains (losses) included in: net income	48	(28)
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	0	0
Issues	(8)	0
Settlements	5	1
Balance at the end of the period	(417)	(251)
Total	19	(2)
Realized capital gains and losses
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	(6)	26
Net investment income
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	(23)	0
Interest credited to contractholder funds
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	72	(36)
Life contract benefits
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	(24)	8
Contractholder funds: Derivatives embedded in life and annuity contracts
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Calculation
Balance at the beginning of the period	(462)	(224)
Total gains (losses) included in: net income	48	(28)
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	0	0
Issues	(8)	0
Settlements	5	1
Balance at the end of the period	(417)	(251)
Municipal
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	62	70
Total gains (losses) included in: net income	1	0
Total gains (losses) included in: OCI	(1)	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	(2)	(2)
Issues	0	0
Settlements	(2)	(1)
Balance at end of period	58	68
Corporate - public
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	61	70
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	20
Sales	0	0
Issues	0	0
Settlements	(1)	(1)
Balance at end of period	60	90
Corporate - privately placed
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	114	90
Total gains (losses) included in: net income	0	(2)
Total gains (losses) included in: OCI	(1)	2
Transfers into Level 3	0	15
Transfers out of Level 3	(25)	0
Purchases	1	0
Sales	0	(13)
Issues	0	0
Settlements	(1)	(2)
Balance at end of period	88	90
MBS
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	40	26
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	3
Transfers out of Level 3	0	0
Purchases	0	6
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	40	35
Fixed income securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	342	325
Total gains (losses) included in: net income	1	(2)
Total gains (losses) included in: OCI	(2)	4
Transfers into Level 3	26	18
Transfers out of Level 3	(74)	(47)
Purchases	34	104
Sales	(11)	(25)
Issues	0	0
Settlements	(31)	(7)
Balance at end of period	285	370
Equity securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	371	341
Total gains (losses) included in: net income	(30)	28
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	1	2
Sales	0	(68)
Issues	0	0
Settlements	0	0
Balance at end of period	342	303
Short-term investments
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	25	30
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	25	10
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	50	40
Free-standing derivatives, net
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period		1
Total gains (losses) included in: net income		0
Total gains (losses) included in: OCI		0
Transfers into Level 3		0
Transfers out of Level 3		0
Purchases		0
Sales		0
Issues		0
Settlements		0
Balance at end of period		1
ABS
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	65	69
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	26	0
Transfers out of Level 3	(49)	(47)
Purchases	33	78
Sales	(9)	(10)
Issues	0	0
Settlements	(27)	(3)
Balance at end of period	$ 39	$ 87

Amount of gain (loss) recognized in income from asset and liability measured at fair value on recurring basis using unobservable input (level 3).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of transfers of financial instrument classified as a liability into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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