Restructuring Costs - Restructuring Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 77	$ 43	$ 0
Additions related to merger integration	12	52	44
Reductions related to severance payments	(42)	(18)	(1)
Balance at end of period	$ 47	$ 77	$ 43