Income Taxes - Schedule of Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current, Federal	$ 670	$ 759	$ 1,067
Current, State	134	149	120
Current, Foreign	17	23	19
Deferred, Federal	254	9	423
Deferred, State	29	13	3
Deferred, Foreign	(5)	(7)	6
Provision for income taxes	$ 1,099	$ 946	$ 1,638