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, 2017	Dec. 31, 2016	Dec. 31, 2015
Self-Insurance Reserve for Losses and Loss Adjustment Expenses [Roll Forward]
Balance at beginning of year	$ 522	$ 416
Less: Reinsurance recoverable	(3)	(3)	$ (3)
Net balance at beginning of year	519	413
Assumed in the Starwood Combination	0	91
Incurred related to:
Current year	163	140
Prior years	(46)	(20)
Total incurred	117	120
Paid related to:
Current year	(30)	(26)
Prior years	(74)	(79)
Total paid	(104)	(105)
Net balance at end of year	532	519
Add: Reinsurance recoverable	3	3	$ 3
Balance at end of year	535	522
Current portion classified in “Accrued expenses and other”	146	142
Noncurrent portion classified in “Other noncurrent liabilities”	$ 389	$ 380