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	Mar. 31, 2023		Dec. 31, 2022
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	$ 56,085	[1]	$ 52,901	[2]
Equity Method Investments, Fair Value Disclosure	138	[1]	134	[2]
Funds withheld at interest embedded derivatives	(322)	[1]	(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	53	[1]	54	[2]
Cash and cash equivalents	1,654	[1]	1,535	[2]
Short-term investments	203	[1]	121	[2]
Derivative Assets (Liabilities), at Fair Value, Net	100	[1]	170	[2]
Investments, Fair Value Disclosure	124	[1]	193	[2]
Assets, Fair Value Disclosure	57,935	[1]	54,567	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	495		530
Funds Held under Reinsurance Agreements, Liability	(351)		(363)
Other liabilities	(189)		(183)
Financial Liabilities Fair Value Disclosure	333		350
Fair Value, Net Asset (Liability)	726
Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	24	[1]	23	[2]
Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	35,477	[1]	33,969	[2]
Canadian and Canadian provincial governments
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,755	[1]	3,626	[2]
Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,024	[1]	941	[2]
Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	4,103	[1]	3,878	[2]
Assets, Fair Value Disclosure	272		274
Commercial Mortgage Backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,670	[1]	1,623	[2]
US Treasury and Government [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,745	[1]	1,482	[2]
US States and Political Subdivisions Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,138	[1]	1,119	[2]
Debt Security, Government, Non-US [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,730	[1]	3,704	[2]
Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,443	[1]	2,559	[2]
Fair Value Inputs Level 1 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,649	[1]	1,388	[2]
Equity Method Investments, Fair Value Disclosure	70	[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	1,653	[1]	1,535	[2]
Short-term investments	118	[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	3,490	[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	1,649	[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	48,297	[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	0	[1]	0	[2]
Short-term investments	78	[1]	54	[2]
Derivative Assets (Liabilities), at Fair Value, Net	100	[1]	170	[2]
Investments, Fair Value Disclosure	124	[1]	193	[2]
Assets, Fair Value Disclosure	48,499	[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	(189)		(183)
Financial Liabilities Fair Value Disclosure	189		183
Fair Value Inputs Level 2 Member | Fair Value Option Contractholder Directed Unit Linked Investments [Member]
Assets Fair Value Disclosure
Investments, Fair Value Disclosure	24	[1]	23	[2]
Fair Value Inputs Level 2 Member | Corporate Debt Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	30,864	[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	3,755	[1]	3,626	[2]
Fair Value Inputs Level 2 Member | Residential mortgage-backed securities
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	1,023	[1]	931	[2]
Fair Value Inputs Level 2 Member | Asset-backed Securities [Member]
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	2,699	[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	1,614	[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	88	[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	1,118	[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	3,693	[1]	3,669	[2]
Fair Value Inputs Level 2 Member | Japanese Government
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	3,443	[1]	2,559	[2]
Fair Value Inputs Level 3 Member
Assets Fair Value Disclosure
Fixed maturity securities, available-for-sale	6,139	[1]	5,722	[2]
Equity Method Investments, Fair Value Disclosure	68	[1]	66	[2]
Funds withheld at interest embedded derivatives	(322)	[1]	(371)	[2]
Funds Held Under Reinsurance Agreements, Asset Fair Value Disclosure	53	[1]	54	[2]
Cash and cash equivalents	1	[1]	0	[2]
Short-term investments	7	[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	5,946	[1]	5,484	[2]
Liabilities Fair Value Disclosure
Fair Value Measured On Recurring Basis Guaranteed Interest Contracts Embedded Derivatives	495		530
Funds Held under Reinsurance Agreements, Liability	(351)		(363)
Other liabilities	0		0
Financial Liabilities Fair Value Disclosure	144		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	4,613	[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	1,404	[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	56	[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	20	[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	37	[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 March 31, 2023, the fair value of such investments was $726 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