Leases - Components of lease expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Components of lease expense
Operating lease expense	$ (94)	$ (75)
Finance lease expense	(2)	(1)
Variable lease expense	(20)	(16)
Sublease income	3	2
Net lease expense	$ (113)	$ (90)