Investments (Investments in Fixed Maturity and Equity Securities Available-for-Sale by Sector) (Details) - USD ($) $ in Millions	Sep. 30, 2023		Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	$ 62,332		$ 59,663
Fixed maturity securities, available-for-sale	54,171	[1]	52,901	[2]
Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	62,332		59,663
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	390		594
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	8,483		7,319
Fixed maturity securities, available-for-sale	$ 54,171		$ 52,901
% of Total	100.00%		100.00%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 68		$ 37
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	41,463		38,963
Fixed maturity securities, available-for-sale	$ 35,503	[1]	$ 33,969	[2]
% of Total	100.00%		100.00%
Corporate Debt Securities [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	$ 41,463		$ 38,963
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	170		168
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	6,075		5,135
Fixed maturity securities, available-for-sale	$ 35,503		$ 33,969
% of Total	65.50%		64.20%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 55		$ 27
Canadian and Canadian provincial governments
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	3,348	[1]	3,626	[2]
Canadian and Canadian provincial governments | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	3,336		3,311
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	169		381
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	157		66
Fixed maturity securities, available-for-sale	$ 3,348		$ 3,626
% of Total	6.20%		6.90%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	1,030	[1]	941	[2]
Residential mortgage-backed securities | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,172		1,054
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	145		114
Fixed maturity securities, available-for-sale	$ 1,030		$ 941
% of Total	1.90%		1.80%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	4,236	[1]	3,878	[2]
Asset-backed Securities [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	4,562		4,324
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	16		4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	330		440
Fixed maturity securities, available-for-sale	$ 4,236		$ 3,878
% of Total	7.80%		7.30%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 12		$ 10
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	1,710	[1]	1,623	[2]
Commercial Mortgage Backed Securities [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,959		1,835
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	250		212
Fixed maturity securities, available-for-sale	$ 1,710		$ 1,623
% of Total	3.20%		3.10%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 1		$ 0
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	1,060	[1]	1,482	[2]
US Treasury and Government [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,346		1,690
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0		4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	286		212
Fixed maturity securities, available-for-sale	$ 1,060		$ 1,482
% of Total	2.00%		2.80%
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]
Fixed maturity securities, available-for-sale	1,047	[1]	1,119	[2]
US States and Political Subdivisions Debt Securities [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,242		1,282
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4		10
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	199		173
Fixed maturity securities, available-for-sale	$ 1,047		$ 1,119
% of Total	1.90%		2.10%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
Debt Security, Government, Non-US [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	3,522	[1]	3,704	[2]
Debt Security, Government, Non-US [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	4,047		4,171
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	23		22
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	548		489
Fixed maturity securities, available-for-sale	$ 3,522		$ 3,704
% of Total	6.50%		7.00%
Debt Securities, Available-for-Sale, Allowance for Credit Loss	$ 0		$ 0
JAPAN | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	3,205		3,033
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3		4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	493		478
Fixed maturity securities, available-for-sale	$ 2,715		$ 2,559
% of Total	5.00%		4.80%
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 September 30, 2023, the fair value of such investments was $818 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, 2022, the fair value of such investments was $683 million