Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	22.50%	5.60%
IRS
Income Tax Examination [Line Items]
Possible increase in U.S. taxable income	$ 696
Possible additional federal tax expense	$ 244