Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	18.40%	21.50%	18.80%	20.10%
Effective tax rate, decrease from comparative period (as a percent)	3.10%		1.30%
Unrecognized tax benefits that would affect the effective tax rate	$ 1,105		$ 1,105		$ 1,145
Deferred tax assets valuation allowance	$ 158		$ 158		$ 135