Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Unrecognized tax benefits:
Balance, January 1	$ 227	$ 173	$ 190
Increases as a result of tax positions taken during the current year	26	18	14
Decreases of tax positions taken during prior years	(20)	(5)	(21)
Increases of tax positions taken during prior years	40	57	20
Decreases as a result of settlements with taxing authorities and the expiration of statutes of limitations	(23)	(19)	(30)
Effect of foreign currency rate movements	(5)	3	0
Balance, December 31	$ 245	$ 227	$ 173