Capital Stock - Accumulated Other Comprehensive Loss (Details) - 2.5% (€650 million) senior notes due 2022 - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation losses, net of tax	$ 40	$ 69
Foreign currency translation losses, before tax	$ 53	$ 90
Debt, interest rate (percentage)	2.50%	2.50%