SELF-INSURANCE RESERVE FOR LOSSES AND LOSS ADJUSTMENT EXPENSES - Activity in Self-Insurance Reserves for Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Self-Insurance Reserve for Losses and Loss Adjustment Expenses [Roll Forward]
Balance at beginning of year	$ 487	$ 493
Less: Reinsurance recoverable	(7)	(3)	$ (3)
Net balance at beginning of year	484	490
Incurred related to:
Current year	151	160
Prior years	(37)	(59)
Total incurred	114	101
Paid related to:
Current year	(32)	(30)
Prior years	(96)	(77)
Total paid	(128)	(107)
Net balance at end of year	470	484
Add: Reinsurance recoverable	7	3	$ 3
Balance at end of year	477	487
Current portion classified in “Accrued expenses and other”	126	112
Noncurrent portion classified in “Other noncurrent liabilities”	$ 351	$ 375