Fair Value - Gross Realized Gains and Losses and Investment Income on Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Realized gains			$ 1
Realized losses	$ (2)	$ (2)	$ (1)