PROPERTY AND EQUIPMENT, NET - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 505	$ 444	$ 410
Amortization expense for capitalized internally developed and purchased software	$ 343	$ 298	$ 287