Summary of Significant Accounting Policies - Computation of Weighted Average Basic and Diluted Shares Outstanding (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss attributable to Company	$ (2,542)	$ (6,095)	$ (31)
Denominator:
Basic—weighted average common shares outstanding	384	382	378
Dilutive effect of employee stock options and other unvested stock awards	0	0	0
Diluted outstanding shares	384	382	378
Basic loss attributable to Company per share	$ (6.62)	$ (15.96)	$ (0.08)
Diluted loss attributable to Company per share	(6.62)	(15.96)	(0.08)
Cash dividends per share	$ 0.05	$ 0.20	$ 0.20