Investments (Exposure To Concentrations Of Credit Risk) (Details) - USD ($) $ in Millions	Dec. 31, 2024		Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	$ 77,617	[1]	$ 60,467	[2]
Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	77,617		60,467
Japanese Government Debt Securities Member
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	5,319		3,630
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	4,445		3,131
Japanese Government Debt Securities Member | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	4,445		3,131
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	2,734		2,725
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	2,464	[1]	2,520	[2]
US Treasury and Government [Member] | Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	2,464		2,520
Canadian Province Of Ontario Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,117		1,019
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	1,207		1,125
Canadian Province Of Quebec Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for Sale at Fair value - Amortized cost	1,537		1,467
Fixed maturity securities available-for-sale at fair value (amortized cost of $82,907 and $64,977; allowance for credit losses of $98 and $75)	$ 1,741		$ 1,748

[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, 2024, the fair value of such investments was $966 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.