Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	Jun. 30, 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	$ 13,532	$ 31,631
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	656	3,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	31,086	12,915
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,937	3,615
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	44,618	44,546
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	6,593	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	13,035	30,773
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	634	3,598
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	30,190	12,408
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,778	3,485
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	43,225	43,181
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	6,412	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	497	858
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	22	95
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	896	507
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	159	130
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,393	1,365
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	181	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	9,095	21,867
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	496	2,756
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	19,800	6,840
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4,161	2,225
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	28,895	28,707
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	4,657	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	481	767
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	21	87
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	660	305
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	83	61
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,141	1,072
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	104	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	436	554
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	42
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	168	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	604	625
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	47	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	385	664
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	62
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	532	181
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	94	53
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	917	845
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	111	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	503	1,596
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	153
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,069	1,931
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	316	269
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,572	3,527
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	333	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	16	52
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	53	38
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	13	9
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	69	90
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	14	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	331	1,314
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	16	144
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,311	281
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	212	65
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,642	1,595
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	228	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	749	1,202
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	14	64
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	596	253
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	194	148
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,345	1,455
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	208	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	303	819
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	13	124
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	660	131
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	132	50
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	963	950
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	145	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	988	1,942
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	42	167
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,900	1,026
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	362	260
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,888	2,968
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	404	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	183	164
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	63	60
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	183	203
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	63	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	245	815
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	86
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,154	1,694
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	277	392
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,399	2,509
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 279	$ 478