Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 82	$ 71	$ 52
Increases related to prior year tax positions	26	24	9
Decreases related to prior year tax positions	(1)	0	(1)
Settlements	(15)	(11)	(2)
Foreign currency impact	(7)	(2)	(5)
Increases related to current year tax positions	0	0	21
Lapse of statute of limitations	0	0	(3)
Balance at end of period	$ 85	$ 82	$ 71