Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Millions	Mar. 31, 2025		Dec. 31, 2024		Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	$ 89,709		$ 82,907
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,348		1,201
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	6,447		6,393
Fixed maturity securities, available-for-sale	$ 84,507	[1]	$ 77,617	[2]
% of Total	100.00%		100.00%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 103		$ 98		$ 95	$ 75
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	59,278		54,705
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	680		642
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	4,150		4,274
Fixed maturity securities, available-for-sale	$ 55,720	[1]	$ 50,991	[2]
% of Total	65.90%		65.70%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 88		$ 82		79	62
Canadian and Canadian provincial governments
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	4,604		4,655
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	440		412
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	48		51
Fixed maturity securities, available-for-sale	$ 4,996	[1]	$ 5,016	[2]
% of Total	5.90%		6.50%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,571		1,412
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	18		12
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	87		107
Fixed maturity securities, available-for-sale	$ 1,502	[1]	$ 1,317	[2]
% of Total	1.80%		1.70%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	5,666		5,197
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	44		42
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	175		184
Fixed maturity securities, available-for-sale	$ 5,520	[1]	$ 5,040	[2]
% of Total	6.50%		6.50%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 15		$ 15		15	12
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	2,334		2,344
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	20		22
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	87		98
Fixed maturity securities, available-for-sale	$ 2,267	[1]	$ 2,267	[2]
% of Total	2.70%		2.90%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 1		$ 1	$ 1
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	2,191		2,734
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	20		11
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	248		281
Fixed maturity securities, available-for-sale	$ 1,963	[1]	$ 2,464	[2]
% of Total	2.30%		3.20%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	805		789
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3		3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	86		99
Fixed maturity securities, available-for-sale	$ 722	[1]	$ 693	[2]
% of Total	0.90%		0.90%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Debt Security, Government, Non-US [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	6,053		5,752
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	94		56
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	435		424
Fixed maturity securities, available-for-sale	$ 5,712	[1]	$ 5,384	[2]
% of Total	6.80%		6.90%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
JAPAN
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	7,207		5,319
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	29		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,131		875
Fixed maturity securities, available-for-sale	$ 6,105		$ 4,445
% of Total	7.20%		5.70%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0

[1] Excludes limited partnerships that are measured at estimated fair value using the NAV per share (or its equivalent) as a practical expedient. As of March 31, 2025, the fair value of such investments was $963 million.

[2] Excludes limited partnerships that are measured at estimated fair value using the NAV per share (or its equivalent) as a practical expedient. As of December 31, 2024, the fair value of such investments was $966 million