Income Taxes - Reconciliation of Uncertain Tax Positions (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits
Unrecognized tax positions, beginning balance	$ 495	$ 389	$ 200
Additions for tax positions related to the current year	35	80	86
Additions for tax positions of prior years	22	89	120
Reductions for tax positions of prior years	(2)	(13)	(4)
Settlements with taxing authorities	(1)	(2)	(2)
Lapse of statute of limitations	(44)	(48)	(11)
Reclassification to indemnification liability related to MAKS divestiture	(28)	0	0
Unrecognized tax positions, ending balance	$ 477	$ 495	$ 389