Supplemental financial information - Restructuring balances (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Balance, January 1		$ 18	$ 0	$ 28
Restructuring charges	[1]	0	25	(15)
Non-cash items	[2]	0		0
Non-cash items	[2]		1
Payments		(13)	(8)	(13)
Balance, December 31		$ 5	$ 18	$ 0

[1] Includes severance and benefits, accelerated depreciation, changes in estimates and other exit costs.

[2] Reflects charges for impacts of changes in exchange rates and accelerated depreciation.