Income Taxes - Income (Loss) Before Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income before taxes, United States	$ (4,394)	$ (8,991)	$ (55)
Income before taxes, Outside United States	(6,904)	(1,427)	2,679
Income (loss) before taxes	$ (11,298)	$ (10,418)	$ 2,624