INCOME TAXES - Types of Temporary Differences and Carry-Forwards that Significantly Effect Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets
Employee benefits	$ 267	$ 261
Net operating loss carry-forwards	680	494
Accrued expenses and other reserves	162	160
Receivables, net	11	12
Tax credits	41	24
Loyalty Program	249	133
Deferred income	70	56
Lease liabilities	261	0
Other	15	13
Deferred tax assets	1,756	1,153
Valuation allowance	(616)	(428)
Deferred tax assets after valuation allowance	1,140	725
Deferred Tax Liabilities
Joint venture interests	(55)	(59)
Property and equipment	(82)	(85)
Intangibles	(895)	(876)
Right-of-use assets	(229)	0
Self-insurance	(15)	(19)
Deferred tax liabilities	(1,276)	(1,039)
Net deferred taxes	$ (136)	$ (314)