COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Operating Lease, Types [Line Items]
2016	$ 92,552
2017	80,262
2018	71,612
2019	61,286
2020	52,957
After 2020	106,859
Total	465,528
Office Leases [Member]
Operating Lease, Types [Line Items]
Operating Leases, Rent Expense, Net	64,800	$ 57,200	$ 40,000
Data Center Space, Leases [Member]
Operating Lease, Types [Line Items]
Operating Leases, Rent Expense, Net	$ 21,600	$ 14,900	$ 12,500
Norwalk, Connecticut [Member] | Parent Company [Member]
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	102,000
Amsterdam, Netherlands [Member] | Booking.com
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	258,000
Stamford, Connecticut [Member] | KAYAK
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	18,000
Bangkok, Thailand [Member] | agoda [Member]
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	95,000
San Francisco, California [Member] | OpenTable
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	51,000
Manchester, England [Member] | Rentalcars Dot Com [Member]
Operating Lease, Types [Line Items]
Area of Real Estate Property | ft²	45,000