DESCRIPTION OF BUSINESS AND BASIS FOR PRESENTATION (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Jan. 01, 2019
Capitalized Contract Cost [Line Items]
Contracts invoiced in arrears, duration	1 month
Capitalized contract cost, amortization period threshold for practical expedient	12 months
Minimum | Scenario, Forecast | Accounting Standards Update 2018-11
Capitalized Contract Cost [Line Items]
Operating lease right-of-use asset		$ 240
Operating lease liability		270
Maximum
Capitalized Contract Cost [Line Items]
Capitalized contract cost, amortization period	41 months
Maximum | Scenario, Forecast | Accounting Standards Update 2018-11
Capitalized Contract Cost [Line Items]
Operating lease right-of-use asset		260
Operating lease liability		$ 290
Advertising services
Capitalized Contract Cost [Line Items]
Contracts invoiced in arrears, duration	1 month
Payment collection after billing period, duration	30 days
Transaction services
Capitalized Contract Cost [Line Items]
Payment collection after billing period, duration	30 days
Subscription services
Capitalized Contract Cost [Line Items]
Contracts invoiced in advance, duration	1 month