Self-Insurance Reserve for Losses and Loss Adjustment Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Self-Insurance Reserve for Losses and Loss Adjustment Expenses [Roll Forward]
Balance at beginning of year	$ 384	$ 362
Less: reinsurance recoverable	4	5
Net balance at beginning of year	380	357
Incurred related to:
Current year	141	126
Prior years	(11)	(2)
Total incurred	130	124
Paid related to:
Current year	(27)	(24)
Prior years	(70)	(77)
Total paid	(97)	(101)
Net balance at end of year	413	380
Add: reinsurance recoverable	3	4
Balance at end of year	416	384
Current portion classified in “Accrued expenses and other”	115	120
Noncurrent portion classified in “Other noncurrent liabilities”	$ 301	$ 264