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, 2022	Dec. 31, 2021
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	$ 26,488	$ 10,644
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,677	176
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,963	2,640
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	376	171
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	29,451	13,284
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	2,053	347
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	25,388	10,045
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,608	156
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,735	2,455
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	317	104
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	28,123	12,500
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,925	260
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	1,100	599
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	69	20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	228	185
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	59	67
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,328	784
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	128	87
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	15,156	4,135
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,082	86
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,161	946
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	186	51
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	16,317	5,081
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,268	137
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	878	463
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	50	13
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	108	97
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33	44
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	986	560
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	83	57
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	127	20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	15	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	142	20
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	12	1
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	400	132
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	137	102
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	13	4
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	537	234
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	28	7
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	2,632	1,747
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	139	22
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	604	589
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	18	6
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,236	2,336
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	157	28
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	22	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	9	13
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	13
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	31	13
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	4	13
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	1,178	152
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	40	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	34	35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,212	187
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	43	4
Commercial mortgage-backed securities | 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	28	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	9	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	37	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	3	0
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	1,148	1,513
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	64	6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	27	31
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,175	1,544
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69	8
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	460	109
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	42	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	30	28
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	490	137
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	47	5
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	4,287	2,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	218	33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	727	724
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	83	37
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	5,014	2,961
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	301	70
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	172	136
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	102	75
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	23	10
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	274	211
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 38	$ 17