Investments (Rollforward of expected credit losses HTM) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Debt Securities, Held to maturity, Allowance for Credit Loss	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 33	$ 34
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Recovery	$ 0	$ (33)	$ 0	$ (34)