ACQUISITIONS (Details for Apartment Finder) $ in Thousands			12 Months Ended
	Jun. 01, 2015 USD ($) distinct_intangible_asset	Apr. 03, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Business Acquisition [Line Items]
Payments to acquire businesses		$ 587,104
Closing purchase price adjustments		2,104
Post closing purchase price adjustments		$ (2,886)
Goodwill			$ 1,252,945	$ 1,138,805	$ 718,587
Apartment Finder [Member]
Business Acquisition [Line Items]
Percentage of outstanding stock acquired	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
Acquired Trade Names and Other Intangible Assets [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets			12 years
Acquired Trade Names and Other Intangible Assets [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	9 years
Acquired Customer Base [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets			10 years
Acquired Customer Base [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
Acquired Database Technology [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets			5 years
Acquired Database Technology [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	5 months
Acquired Building Photography [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets			4 years
Acquired Building Photography [Member] | Apartment Finder [Member]
Business Acquisition [Line Items]
Estimated useful life of acquired assets	5 months