Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Federal
Current	$ 353	$ 315
Deferred	130	(106)
Federal income tax	483	209
State
Current	94	70
Deferred	30	(19)
State income tax	124	51
Applicable income taxes	$ 607	$ 260