Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 15,046	$ 31,631
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	693	3,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	28,930	12,915
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,403	3,615
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	43,976	44,546
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	6,096	7,308
Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	14,451	30,773
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	632	3,598
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	28,151	12,408
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,253	3,485
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	42,602	43,181
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	5,885	7,083
Non-investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	595	858
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	61	95
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	779	507
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	150	130
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,374	1,365
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	211	225
Corporate Debt Securities [Member] | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	9,861	21,867
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	486	2,756
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,130	6,840
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,705	2,225
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	27,991	28,707
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	4,191	4,981
Corporate Debt Securities [Member] | Non-investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	550	767
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	58	87
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	546	305
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	79	61
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,096	1,072
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	137	148
Canadian and Canadian provincial governments | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	395	554
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15	42
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	165	71
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	30	23
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	560	625
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	45	65
Residential mortgage-backed securities | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	332	664
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	16	62
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	513	181
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	82	53
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	845	845
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	98	115
Asset-backed Securities [Member] | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	811	1,596
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	38	153
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,777	1,931
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	311	269
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,588	3,527
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	349	422
Asset-backed Securities [Member] | Non-investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	45	52
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	46	38
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	10	9
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	91	90
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	13	15
Commercial mortgage-backed securities | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	341	1,314
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	20	144
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,271	281
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	188	65
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,612	1,595
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	208	209
US Government Agencies Debt Securities [Member] | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	909	1,202
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5	64
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	606	253
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	179	148
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,515	1,455
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	184	212
US States and Political Subdivisions Debt Securities [Member] | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	350	819
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	10	124
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	635	131
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	122	50
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	985	950
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	132	174
Debt Security, Government, Non-US [Member] | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,073	1,942
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	38	167
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,763	1,026
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	325	260
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,836	2,968
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	363	427
Debt Security, Government, Non-US [Member] | Non-investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	39
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	187	164
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	61	60
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	187	203
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	61	62
JAPAN | Investment grade securities
Estimated Fair Values And Gross Unrealized Losses, OTTI Impairment Losses Reported In AOCI [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	379	815
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	86
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,291	1,694
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	311	392
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,670	2,509
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 315	$ 478