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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	$ 677	$ 714	$ 738	$ 697
Total gains (losses) included in: net income	16	10	(15)	36
Total gains (losses) included in: OCI	(13)	2	(15)	6
Transfers into Level 3	69	2	80	20
Transfers out of Level 3	(65)	(115)	(99)	(162)
Purchases	112	72	140	188
Sales	(21)	(72)	(22)	(165)
Issues	0	0	0	0
Settlements	(1)	(3)	(33)	(10)
Balance at end of period	774	610	774	610
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Calculation
Balance at the beginning of the period	(417)	(251)	(462)	(224)
Total gains (losses) included in: net income	(69)	(12)	(21)	(40)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	(175)	0	(175)
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(7)	0	(15)	0
Settlements	5	1	10	2
Balance at the end of the period	(488)	(437)	(488)	(437)
Total	(53)	(2)	(36)	(4)
Net investment income
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	1	5	(23)	5
Realized capital gains and losses
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	15	5	8	31
Interest credited to contractholder funds
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	10	(5)	(14)	3
Interest credited to contractholder funds
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Total gains (losses) included in: net income	(79)	(7)	(7)	(43)
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	(417)	(251)	(462)	(224)
Total gains (losses) included in: net income	(69)	(12)	(21)	(40)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	(175)	0	(175)
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(7)	0	(15)	0
Settlements	5	1	10	2
Balance at the end of the period	(488)	(437)	(488)	(437)
Municipal
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	58	68	62	70
Total gains (losses) included in: net income	1	0	1	0
Total gains (losses) included in: OCI	2	1	2	2
Transfers into Level 3	15	0	14	0
Transfers out of Level 3	0	(5)	0	(5)
Purchases	8	0	8	0
Sales	(1)	(1)	(2)	(3)
Issues	0	0	0	0
Settlements	0	0	(2)	(1)
Balance at end of period	83	63	83	63
Corporate - public
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	60	90	61	70
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	(8)	1	(8)	2
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(40)	0	(40)
Purchases	15	0	15	20
Sales	0	(5)	0	(5)
Issues	0	0	0	0
Settlements	0	0	(1)	(1)
Balance at end of period	67	46	67	46
Corporate - privately placed
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	88	90	114	90
Total gains (losses) included in: net income	1	1	1	(1)
Total gains (losses) included in: OCI	(4)	0	(5)	2
Transfers into Level 3	11	0	11	15
Transfers out of Level 3	0	(2)	(25)	(2)
Purchases	37	1	38	1
Sales	(6)	0	(6)	(13)
Issues	0	0	0	0
Settlements	(1)	(1)	(2)	(3)
Balance at end of period	126	89	126	89
ABS
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	39	87	65	69
Total gains (losses) included in: net income	1	0	0	0
Total gains (losses) included in: OCI	(2)	0	(3)	0
Transfers into Level 3	43	1	55	1
Transfers out of Level 3	(25)	(68)	(49)	(115)
Purchases	4	46	19	124
Sales	(10)	(12)	(10)	(22)
Issues	0	0	0	0
Settlements	0	(1)	(27)	(4)
Balance at end of period	50	53	50	53
MBS
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	40	35	40	26
Total gains (losses) included in: net income	1	0	1	0
Total gains (losses) included in: OCI	(1)	0	(1)	0
Transfers into Level 3	0	1	0	4
Transfers out of Level 3	0	0	0	0
Purchases	9	0	10	6
Sales	(4)	0	(4)	0
Issues	0	0	0	0
Settlements	0	(1)	(1)	(1)
Balance at end of period	45	35	45	35
Fixed income securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	285	370	342	325
Total gains (losses) included in: net income	4	1	3	(1)
Total gains (losses) included in: OCI	(13)	2	(15)	6
Transfers into Level 3	69	2	80	20
Transfers out of Level 3	(25)	(115)	(74)	(162)
Purchases	73	47	90	151
Sales	(21)	(18)	(22)	(43)
Issues	0	0	0	0
Settlements	(1)	(3)	(33)	(10)
Balance at end of period	371	286	371	286
Equity securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	342	303	371	341
Total gains (losses) included in: net income	12	10	(18)	38
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	39	20	40	22
Sales	0	(14)	0	(82)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	393	319	393	319
Short-term investments
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	50	40	25	30
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(40)	0	(25)	0
Purchases	0	5	10	15
Sales	0	(40)	0	(40)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	$ 10	5	$ 10	5
Free-standing derivatives, net
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period		1		1
Total gains (losses) included in: net income		(1)		(1)
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		0		0
Settlements		0		0
Balance at end of period		$ 0		$ 0