Investments (Fixed Maturity Securities - Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, estimated fair value	$ 80,541		$ 79,129
Fixed maturity securities, allowance for credit losses	$ 62	$ 59	79	$ 21
Fixed maturity securities with allowance for credit losses, number of securities	17
Fixed maturity securities, total write-offs	$ 33	$ 10
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	698		665
Non-Income Producing
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, estimated fair value	$ 15		$ 30