Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Millions	Mar. 31, 2024		Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	$ 70,790		$ 64,977
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	916		1,125
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5,784		5,560
Fixed maturity securities, available-for-sale	$ 65,827	[1]	$ 60,467	[2]
% of Total	100.00%		100.00%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 95		$ 75
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	44,575		42,014
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	485		554
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	3,933		3,751
Fixed maturity securities, available-for-sale	$ 41,048	[1]	$ 38,755	[2]
% of Total	62.40%		64.10%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 79		$ 62
Canadian and Canadian provincial governments
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	3,455		3,477
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	326		473
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	68		33
Fixed maturity securities, available-for-sale	$ 3,713	[1]	$ 3,917	[2]
% of Total	5.60%		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	1,250		1,173
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	10		8
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	110		102
Fixed maturity securities, available-for-sale	$ 1,150	[1]	$ 1,079	[2]
% of Total	1.70%		1.80%
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	5,137		4,661
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	30		19
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	207		239
Fixed maturity securities, available-for-sale	$ 4,945	[1]	$ 4,429	[2]
% of Total	7.50%		7.30%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 15		$ 12
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	2,002		1,969
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	14		7
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	154		202
Fixed maturity securities, available-for-sale	$ 1,861	[1]	$ 1,773	[2]
% of Total	2.80%		2.90%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 1		$ 1
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	3,028		2,725
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2		9
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	244		214
Fixed maturity securities, available-for-sale	$ 2,786	[1]	$ 2,520	[2]
% of Total	4.20%		4.20%
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	1,249		1,236
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6		7
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	139		129
Fixed maturity securities, available-for-sale	$ 1,116	[1]	$ 1,114	[2]
% of Total	1.70%		1.80%
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	4,372		4,092
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	39		45
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	407		388
Fixed maturity securities, available-for-sale	$ 4,004	[1]	$ 3,749	[2]
% of Total	6.20%		6.20%
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	5,722		3,630
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4		3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	522		502
Fixed maturity securities, available-for-sale	$ 5,204		$ 3,131
% of Total	7.90%		5.20%
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, 2024, the fair value of such investments was $893 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, 2023, the fair value of such investments was $856 million