Income Taxes - Deferred Tax Amounts Classified in the Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Noncurrent deferred tax assets	$ 838	$ 776
Noncurrent deferred tax liabilities	(414)	(625)
Net deferred tax assets	$ 424	$ 151