INCOME TAXES - Types of Temporary Differences and Carry-Forwards that Significantly Effect Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets
Employee benefits	$ 261	$ 264
Net operating loss carry-forwards	494	376
Accrued expenses and other reserves	160	161
Receivables, net	12	21
Tax credits	24	27
Loyalty Program	133	31
Deferred income	56	17
Self-insurance	0	12
Other	13	2
Deferred tax assets	1,153	911
Valuation allowance	(428)	(309)
Deferred tax assets after valuation allowance	725	602
Deferred Tax Liabilities
Joint venture interests	(59)	(33)
Property and equipment	(85)	(62)
Intangibles	(876)	(1,019)
Self-insurance	(19)	0
Deferred tax liabilities	(1,039)	(1,114)
Net deferred taxes	$ (314)	$ (512)