Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Federal
Current	$ 354	$ (53)	$ 1,057	$ 966
Deferred	99	306	305	(459)
Federal income tax	453	253	1,362	507
State
Current	94	92	297	298
Deferred	17	2	63	(134)
State income tax	111	94	360	164
Applicable income taxes	$ 564	$ 347	$ 1,722	$ 671