Commitments and Contingencies (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2019	Oct. 31, 2019
Contingencies And Commitments [Line Items]
Maximum self insurance exposures per incident under general liability insurance program	$ 5
Maximum self insurance exposures per incident under workers' compensation insurance program	5
Per incident base deductible under auto liability insurance program	10
Insurance claims receivable	126	$ 130
Beginning Balance	567	582
Self-insurance expense (benefit)	171	142
Cash paid and other	(163)	(157)
Ending Balance	575	567
Current portion	145	137
Long-term portion	$ 430	$ 430
Expected time period in years for cash settlement of recorded obligations associated with insurance liabilities	6 years
Revolving Credit Facility [Member]
Contingencies And Commitments [Line Items]
Credit Facility, aggregate capacity	$ 3,500		$ 3,500	$ 2,750