INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 223,074	$ 198,174	[1]
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	219,924	194,761
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	3,150	3,413
Advertising
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	214,043	177,900
Transactions
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	3,839	18,065
Other services
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 5,192	$ 2,209

[1] As of January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Accordingly, the Company has recast certain amounts in the prior period presented. See Note 1 below for additional discussion.