Leases - Components of lease expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Components of lease expense
Operating lease expense	$ (117)	$ (110)
Finance lease expense	(2)	(2)
Variable lease expense	(17)	(22)
Sublease income	3	3
Net lease expense	$ (133)	$ (131)