Investments (Fair Value and Losses by Investment Category and Length of Time in a Loss Position) (Details) - Fixed Maturities [Member] - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	$ 828	$ 183
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	5,556	5,370
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	6,384	5,553
Debt Securities, Available-for-sale, Unrealized Loss Position	49,888	41,535
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	21,494	4,857
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	28,394	36,678
External Credit Rating, Investment Grade [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	820	147
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	5,463	5,186
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	6,283	5,333
Debt Securities, Available-for-sale, Unrealized Loss Position	48,923	40,326
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	21,046	4,562
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	27,877	35,764
External Credit Rating, Investment Grade [Member] | Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	529	70
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	3,682	3,524
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	4,211	3,594
Debt Securities, Available-for-sale, Unrealized Loss Position	33,592	26,341
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	14,741	2,134
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,851	24,207
External Credit Rating, Investment Grade [Member] | Canadian Provincial Governments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	5	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	46	33
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	51	33
Debt Securities, Available-for-sale, Unrealized Loss Position	755	459
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	286	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	469	459
External Credit Rating, Investment Grade [Member] | Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	19	5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	159	223
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	178	228
Debt Securities, Available-for-sale, Unrealized Loss Position	2,670	3,361
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	940	336
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,730	3,025
External Credit Rating, Investment Grade [Member] | Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	4	5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	91	190
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	95	195
Debt Securities, Available-for-sale, Unrealized Loss Position	1,313	1,488
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	333	160
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	980	1,328
External Credit Rating, Investment Grade [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	7	3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	100	99
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	107	102
Debt Securities, Available-for-sale, Unrealized Loss Position	947	796
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	354	115
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	593	681
External Credit Rating, Investment Grade [Member] | US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	15	10
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	266	204
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	281	214
Debt Securities, Available-for-sale, Unrealized Loss Position	1,448	1,331
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	792	614
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	656	717
External Credit Rating, Investment Grade [Member] | US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	7	1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	92	128
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	99	129
Debt Securities, Available-for-sale, Unrealized Loss Position	572	937
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	155	73
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	417	864
External Credit Rating, Investment Grade [Member] | Debt Security, Government, Non-US [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	42	3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	344	333
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	386	336
Debt Securities, Available-for-sale, Unrealized Loss Position	3,224	2,544
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,408	254
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,816	2,290
External Credit Rating, Investment Grade [Member] | Japanese Government Debt Securities Member
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	192	50
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	683	452
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	875	502
Debt Securities, Available-for-sale, Unrealized Loss Position	4,402	3,069
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,037	876
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,365	2,193
External Credit Rating, Noninvestment Grade [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	8	36
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	93	184
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	101	220
Debt Securities, Available-for-sale, Unrealized Loss Position	965	1,209
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	448	295
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	517	914
External Credit Rating, Noninvestment Grade [Member] | Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	7	36
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	50	121
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	57	157
Debt Securities, Available-for-sale, Unrealized Loss Position	694	944
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	347	295
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	347	649
External Credit Rating, Noninvestment Grade [Member] | Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	5	10
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	6	10
Debt Securities, Available-for-sale, Unrealized Loss Position	141	68
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	101	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	40	68
External Credit Rating, Noninvestment Grade [Member] | Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0	1
Debt Securities, Available-for-sale, Unrealized Loss Position	0	4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	4
External Credit Rating, Noninvestment Grade [Member] | Debt Security, Government, Non-US [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	38	52
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	38	52
Debt Securities, Available-for-sale, Unrealized Loss Position	130	193
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 130	$ 193