Fair Value of Assets and Liabilities (Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2023		Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	$ 60,467	[1]	$ 52,901	[2]
Equity Method Investments, Fair Value Disclosure	139	[1]	134	[2]
Fair Value Measured On Recurring Basis Funds Held Under Reinsurance Agreements Asset Embedded Derivatives	(377)	[1]	(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	54	[1]	54	[2]
Cash and Cash Equivalents, Fair Value Disclosure	1,335	[1]	1,535	[2]
Fair Value Measured On Recurring Basis Short Term Investments	187	[1]	121	[2]
Derivative Assets (Liabilities), at Fair Value, Net	97	[1]	170	[2]
Investments, Fair Value Disclosure	119	[1]	193	[2]
Assets, Fair Value Disclosure	61,924	[1]	54,567	[2]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	415		530
Derivative Liability	(206)		(363)
Funds Held under Reinsurance Agreements, Liability	(4,483)		(1,486)
Other Liabilities, Fair Value Disclosure	197		183
Financial Liabilities Fair Value Disclosure	406		350
Fair Value, Net Asset (Liability)	856		683
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	2,426	[1]	1,388	[2]
Equity Method Investments, Fair Value Disclosure	69	[1]	68	[2]
Fair Value Measured On Recurring Basis Funds Held Under Reinsurance Agreements Asset Embedded Derivatives	0		0	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	0	[1]	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	1,322	[1]	1,535	[2]
Fair Value Measured On Recurring Basis Short Term Investments	90	[1]	54	[2]
Derivative Assets (Liabilities), at Fair Value, Net	0	[1]	0	[2]
Investments, Fair Value Disclosure	0	[1]	0	[2]
Assets, Fair Value Disclosure	3,907	[1]	3,045	[2]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0		0
Derivative Liability	0		0
Other Liabilities, Fair Value Disclosure	0		0
Financial Liabilities Fair Value Disclosure	0		0
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	51,622	[1]	45,791	[2]
Equity Method Investments, Fair Value Disclosure	0	[1]	0	[2]
Fair Value Measured On Recurring Basis Funds Held Under Reinsurance Agreements Asset Embedded Derivatives	0		0	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	0	[1]	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	13	[1]	0	[2]
Fair Value Measured On Recurring Basis Short Term Investments	95	[1]	54	[2]
Derivative Assets (Liabilities), at Fair Value, Net	97	[1]	170	[2]
Investments, Fair Value Disclosure	119	[1]	193	[2]
Assets, Fair Value Disclosure	51,849	[1]	46,038	[2]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0		0
Derivative Liability	0		0
Other Liabilities, Fair Value Disclosure	197		183
Financial Liabilities Fair Value Disclosure	197		183
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	6,419	[1]	5,722	[2]
Equity Method Investments, Fair Value Disclosure	70	[1]	66	[2]
Fair Value Measured On Recurring Basis Funds Held Under Reinsurance Agreements Asset Embedded Derivatives	(377)		(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	54	[1]	54	[2]
Cash and Cash Equivalents, Fair Value Disclosure	0	[1]	0	[2]
Fair Value Measured On Recurring Basis Short Term Investments	2	[1]	13	[2]
Derivative Assets (Liabilities), at Fair Value, Net	0	[1]	0	[2]
Investments, Fair Value Disclosure	0	[1]	0	[2]
Assets, Fair Value Disclosure	6,168	[1]	5,484	[2]
Liabilities, Fair Value Disclosure [Abstract]
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	415		530
Derivative Liability	(206)		(363)
Other Liabilities, Fair Value Disclosure	0		0
Financial Liabilities Fair Value Disclosure	209		167
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, Fair Value Disclosure	22	[1]	23	[2]
Fair Value Option Contractholder Directed Unit Linked Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, Fair Value Disclosure	0	[1]	0	[2]
Fair Value Option Contractholder Directed Unit Linked Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, Fair Value Disclosure	22	[1]	23	[2]
Fair Value Option Contractholder Directed Unit Linked Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Investments, Fair Value Disclosure	0	[1]	0	[2]
Corporate Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	38,755	[1]	33,969	[2]
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	33,822	[1]	29,670	[2]
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	4,933	[1]	4,299	[2]
Canadian Provincial Governments [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,917	[1]	3,626	[2]
Canadian Provincial Governments [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Canadian Provincial Governments [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,917	[1]	3,626	[2]
Canadian Provincial Governments [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Residential Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,079	[1]	941	[2]
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,078	[1]	931	[2]
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1	[1]	10	[2]
Asset-backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	4,429	[1]	3,878	[2]
Assets, Fair Value Disclosure	268		274
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,064	[1]	2,603	[2]
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,365	[1]	1,275	[2]
Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,773	[1]	1,623	[2]
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,714	[1]	1,555	[2]
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	59	[1]	68	[2]
US Treasury and Government [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	2,520	[1]	1,482	[2]
US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	2,426	[1]	1,388	[2]
US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	87	[1]	85	[2]
US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	7	[1]	9	[2]
US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,114	[1]	1,119	[2]
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	1,095	[1]	1,093	[2]
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	19	[1]	26	[2]
Debt Security, Government, Non-US [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,749	[1]	3,704	[2]
Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0	[1]	0	[2]
Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,714	[1]	3,669	[2]
Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	35	[1]	35	[2]
Japanese Government Debt Securities Member
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,131		2,559
Japanese Government Debt Securities Member | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	0		0
Japanese Government Debt Securities Member | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	3,131		2,559
Japanese Government Debt Securities Member | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Fixed maturity securities available-for-sale	$ 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 December 31, 2023, the fair value of such investments was $856 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.