ACQUISITIONS (Details for Apartment Finder) $ in Thousands		9 Months Ended
	Jun. 01, 2015 USD ($) distinct_intangible_asset	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 1,249,945	$ 1,138,805	$ 718,587
Apartment Finder [Member]
Business Acquisition [Line Items]
Percentage of outstanding stock acquired by the Company	100.00%
Payments to acquire businesses	$ 172,706
Closing purchase price adjustments	2,706
Post closing purchase price adjustments	21
Goodwill	107,692
Goodwill tax deductible amount	$ 0
Customer Contracts [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets		10 years
Customer Contracts [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Number of distinct intangible assets | distinct_intangible_asset	3
Estimated useful life of acquired assets	10 years
Developed Technology Rights [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets		5 years
Developed Technology Rights [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	5 months
Trade Names and Other Intangible Assets [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets		12 years
Trade Names and Other Intangible Assets [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	9 years
Building Photography [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets		4 years
Building Photography [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	5 months