Income Taxes - Summary of Tax Provisions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Pre-tax income at estimated annual effective income tax rate before discrete items	$ 34	$ 53
Other discrete items	(1)	(8)
Provision for income taxes	$ 33	$ 45