PROPERTY, EQUIPMENT AND SOFTWARE, NET - Depreciation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 41	$ 35	$ 28
Capitalized internally developed software costs	31	33	29
Depreciation expense for capitalized internally developed software costs	$ 29	$ 24	$ 17