Investments (Fixed Maturity Securities - Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, estimated fair value	$ 74,571		$ 74,757
Fixed maturity securities, allowance for credit losses	$ 22	$ 4	6	$ 11
Fixed maturity securities with allowance for credit losses, number of securities	22
Fixed maturity securities, total write-offs	$ 8	$ 10
Non-Income Producing
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, estimated fair value	12		0
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 681		$ 595