Income Taxes - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Estimated repatriation tax liability resulting from tax reform legislation	$ 247
Revision of estimated repatriation tax liability resulting from tax reform legislation		$ 236
Reduction in estimated repatriation tax liability resulting from tax act			$ 11
Estimated repatriation tax liability resulting from the tax act, pay period					8 years
Excess tax benefits from stock compensation				$ 44	$ 38
Excess tax benefits from stock compensation (percent)				2.42%	2.23%
Valuation allowance	6			$ 9	$ 5	$ 3
Unrecognized tax benefits	$ 389			477	495	$ 200
Uncertain tax positions if recognized would impact the effective tax rate				422
Deferred tax asset for potential transition tax benefit				50	48
Net interest expense on UTPs				28	15
Interest accrued on UTPs				$ 82	$ 70