Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Residential mortgage loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	$ 188	$ 299
Total realized/unrealized gains (losses) included in net income (loss)	9	7	$ 7
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	0	0
Sales	(13)	(87)
Issuances	0	0
Settlements	(19)	(31)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	165	188	299
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	3	(14)	(15)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	3	(14)	(15)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Net Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	67	(129)	(59)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	579
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(146)	(225)
Total realized/unrealized gains (losses) included in net income (loss)	279	(108)	(161)
Total realized/unrealized gains (losses) included in AOCI	761	157	(140)
Purchases	4	4
Sales	0	0
Issuances	(2)	(2)
Settlements	(296)	29
Transfers into Level 3	0	(1)
Transfers out of Level 3	(6)	0
Balance at December 31,	594	(146)	(225)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	67	(129)	(59)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	579
Net Embedded Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(124)	264	(150)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(33)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(742)	(739)
Total realized/unrealized gains (losses) included in net income (loss)	(110)	274	(150)
Total realized/unrealized gains (losses) included in AOCI	(34)	(2)	(15)
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(255)	(275)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	(1,141)	(742)	(739)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(124)	264	(150)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(33)
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	14,229	10,467
Total realized/unrealized gains (losses) included in net income (loss)	(88)	(49)	9
Total realized/unrealized gains (losses) included in AOCI	1,774	893	(745)
Purchases	5,013	3,689
Sales	(1,107)	(870)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	4,985	606
Transfers out of Level 3	(705)	(507)
Balance at December 31,	24,101	14,229	10,467
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(48)	(50)	1
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	1,754
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(48)	(50)	1
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	1,754
Corporate fixed maturity securities | Metropolitan Property And Casualty Insurance Company [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers out of Level 3	137
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	117	138
Total realized/unrealized gains (losses) included in net income (loss)	(2)	0	3
Total realized/unrealized gains (losses) included in AOCI	(1)	(2)	(14)
Purchases	29	10
Sales	(8)	(24)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	6	20
Transfers out of Level 3	(24)	(25)
Balance at December 31,	117	117	138
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(1)	0	1
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(1)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(1)	0	1
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(1)
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	4,458	4,266
Total realized/unrealized gains (losses) included in net income (loss)	49	46	82
Total realized/unrealized gains (losses) included in AOCI	41	42	(23)
Purchases	1,975	1,338
Sales	(918)	(737)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	127	0
Transfers out of Level 3	(443)	(497)
Balance at December 31,	5,289	4,458	4,266
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	54	44	70
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	47
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	54	44	70
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	47
Structured Securities | Metropolitan Property And Casualty Insurance Company [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers out of Level 3	29
Municipals
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	7	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	0	7
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(7)	0
Balance at December 31,	0	7	0
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	430	419
Total realized/unrealized gains (losses) included in net income (loss)	12	47	(36)
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	11	65
Sales	(156)	(98)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(147)	(3)
Balance at December 31,	150	430	419
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	2	39	(26)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	2	39	(26)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Unit-linked and FVO Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	625	405
Total realized/unrealized gains (losses) included in net income (loss)	67	48	6
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	47	203
Sales	(101)	(39)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	154	20
Transfers out of Level 3	(91)	(12)
Balance at December 31,	701	625	405
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	69	48	8
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	69	48	8
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	32	33
Total realized/unrealized gains (losses) included in net income (loss)	(7)	0	(1)
Total realized/unrealized gains (losses) included in AOCI	4	(1)	(1)
Purchases	38	31
Sales	(17)	(33)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	9	2
Transfers out of Level 3	(16)	0
Balance at December 31,	43	32	33
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(7)	0	(1)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	4
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(7)	0	(1)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	4
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	455	39
Total realized/unrealized gains (losses) included in net income (loss)	19	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	99	416
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	573	455	39
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	24	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	24	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	980	937
Total realized/unrealized gains (losses) included in net income (loss)	(5)	7	7
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	270	191
Sales	(159)	(151)
Issuances	(4)	(3)
Settlements	1	2
Transfers into Level 3	1	0
Transfers out of Level 3	(5)	(3)
Balance at December 31,	1,079	980	937
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	$ 0	$ 0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	$ 0