Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2023		Dec. 31, 2022
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 56,236	[1]	$ 52,901	[2]
Equity Method Investments, Fair Value Disclosure	136	[1]	134	[2]
Funds withheld at interest embedded derivatives	(353)	[1]	(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	53	[1]	54	[2]
Cash and cash equivalents	1,329	[1]	1,535	[2]
Short-term investments	193	[1]	121	[2]
Derivative Assets (Liabilities), at Fair Value, Net	61	[1]	170	[2]
Investments, Fair Value Disclosure	82	[1]	193	[2]
Assets, Fair Value Disclosure	57,676	[1]	54,567	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	472		530
Funds Held under Reinsurance Agreements, Liability	(362)		(363)
Other liabilities	(237)		(183)
Financial Liabilities Fair Value Disclosure	347		350
Fair Value, Net Asset (Liability)	768
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	21	[1]	23	[2]
Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	36,178	[1]	33,969	[2]
Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,752	[1]	3,626	[2]
Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,037	[1]	941	[2]
Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	4,165	[1]	3,878	[2]
Assets, Fair Value Disclosure	267		274
Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,699	[1]	1,623	[2]
US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,366	[1]	1,482	[2]
US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,109	[1]	1,119	[2]
Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,884	[1]	3,704	[2]
Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,046	[1]	2,559	[2]
Fair Value Inputs Level 1 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,272	[1]	1,388	[2]
Equity Method Investments, Fair Value Disclosure	68	[1]	68	[2]
Funds withheld at interest embedded derivatives	0	[1]	0	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	0	[1]	0	[2]
Cash and cash equivalents	1,326	[1]	1,535	[2]
Short-term investments	93	[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	2,759	[1]	3,045	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0		0
Funds Held under Reinsurance Agreements, Liability	0		0
Other liabilities	0		0
Financial Liabilities Fair Value Disclosure	0		0
Fair Value Inputs Level 1 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,272	[1]	1,388	[2]
Fair Value Inputs Level 1 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 1 Member | Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 2 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	48,849	[1]	45,791	[2]
Equity Method Investments, Fair Value Disclosure	0	[1]	0	[2]
Funds withheld at interest embedded derivatives	0	[1]	0	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	0	[1]	0	[2]
Cash and cash equivalents	3	[1]	0	[2]
Short-term investments	94	[1]	54	[2]
Derivative Assets (Liabilities), at Fair Value, Net	61	[1]	170	[2]
Investments, Fair Value Disclosure	82	[1]	193	[2]
Assets, Fair Value Disclosure	49,028	[1]	46,038	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	0		0
Funds Held under Reinsurance Agreements, Liability	0		0
Other liabilities	(237)		(183)
Financial Liabilities Fair Value Disclosure	237		183
Fair Value Inputs Level 2 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	21	[1]	23	[2]
Fair Value Inputs Level 2 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	31,524	[1]	29,670	[2]
Fair Value Inputs Level 2 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,752	[1]	3,626	[2]
Fair Value Inputs Level 2 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,036	[1]	931	[2]
Fair Value Inputs Level 2 Member | Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,826	[1]	2,603	[2]
Fair Value Inputs Level 2 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,642	[1]	1,555	[2]
Fair Value Inputs Level 2 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	86	[1]	85	[2]
Fair Value Inputs Level 2 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,088	[1]	1,093	[2]
Fair Value Inputs Level 2 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,849	[1]	3,669	[2]
Fair Value Inputs Level 2 Member | Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,046	[1]	2,559	[2]
Fair Value Inputs Level 3 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	6,115	[1]	5,722	[2]
Equity Method Investments, Fair Value Disclosure	68	[1]	66	[2]
Funds withheld at interest embedded derivatives	(353)	[1]	(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	53	[1]	54	[2]
Cash and cash equivalents	0	[1]	0	[2]
Short-term investments	6	[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	5,889	[1]	5,484	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	472		530
Funds Held under Reinsurance Agreements, Liability	(362)		(363)
Other liabilities	0		0
Financial Liabilities Fair Value Disclosure	110		167
Fair Value Inputs Level 3 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	0	[1]	0	[2]
Fair Value Inputs Level 3 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	4,654	[1]	4,299	[2]
Fair Value Inputs Level 3 Member | Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	0	[1]	0	[2]
Fair Value Inputs Level 3 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1	[1]	10	[2]
Fair Value Inputs Level 3 Member | Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,339	[1]	1,275	[2]
Fair Value Inputs Level 3 Member | Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	57	[1]	68	[2]
Fair Value Inputs Level 3 Member | US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	8	[1]	9	[2]
Fair Value Inputs Level 3 Member | US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	21	[1]	26	[2]
Fair Value Inputs Level 3 Member | Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	35	[1]	35	[2]
Fair Value Inputs Level 3 Member | Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 0	[1]	$ 0	[2]

[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 June 30, 2023, the fair value of such investments was $768 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