THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 702,915		$ 595,038
Deferred tax liability	35,938		35,070
Deferred revenue	$ 374,339		342,483
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ 40,200	$ 3,400
ANGI Homeservices | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		25,900
Current capitalized contract costs		29,700
Noncurrent capitalized contract costs		4,200
Deferred tax liability		8,000
Applications | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		15,500
Deferred tax liability		4,900
Deferred revenue		$ 20,300