COMMITMENTS AND CONTINGENCIES (Details) (USD $)	3 Months Ended		3 Months Ended				1 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended
	Sep. 30, 2013 Litigation Related to Hotel Occupany and Other Taxes [Member] Cases	Dec. 31, 2012 Litigation Related to Hotel Occupany and Other Taxes [Member]	Dec. 31, 2012 Litigation Related to Alleged Anti-trust Violations [Member] Cases	Sep. 30, 2012 Litigation Related to Alleged Anti-trust Violations [Member] Cases	Sep. 30, 2013 Minimum [Member] Litigation Related to Hotel Occupany and Other Taxes [Member] GovernmentalUnit	Sep. 30, 2013 State of California [Member] Minimum [Member] Litigation Related to Hotel Occupany and Other Taxes [Member] GovernmentalUnit	Jan. 31, 2013 City of San Francisco [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Jul. 31, 2009 City of San Francisco [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Mar. 31, 2013 Hawaii [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Dec. 31, 2012 Hawaii [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Sep. 30, 2013 Hawaii [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Sep. 30, 2013 Cities in Arizona Other than Pheonix [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Sep. 30, 2013 Utah [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Sep. 30, 2013 Colorado [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Mar. 31, 2013 District of Columbia [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Sep. 30, 2012 District of Columbia [Member] Litigation Related to Hotel Occupany and Other Taxes [Member]	Jul. 31, 2012 Bookingcom BV [Member] Minimum [Member] UK Office Of Fair Trade Inquiry [Member]	Jul. 31, 2012 Bookingcom BV [Member] Maximum [Member] UK Office Of Fair Trade Inquiry [Member]
Hotel Occupany and Other Taxes
Approximate number of lawsuits brought by or against states, cities and counties over issues involving the payment of hotel occupancy and other taxes (in cases)	40
Minimum number of states which have initiated audit proceedings (in governmental units)					11
Minimum number of municipalities and counties which have initiated audit proceedings (in governmental units)					79	40							5	1
Assessed taxes including interest and penalties (in dollars)							$ 2,700,000	$ 3,400,000	$ 18,700,000	$ 16,500,000					$ 5,600,000	$ 4,800,000
Payments Of Tax And Interest For Loss Contingency Related To Hotel Occupancy And Other Taxes											20,100,000
Reserve for the potential resolution of issues related to hotel occupancy and other taxes (in dollars)	60,000,000	56,000,000
Loss Contingency Audit Proceedings Number of Municipalities and Counties Commencing During Period	4
Loss Contingency, Claims Settled and Dismissed, Number	2
Audit notices and administrative procedures, number of cities						40						12		15
UK OFT Inquiry Potential Infringement Decision																	$ 0	$ 50,000,000
Loss Contingency Complaint Filed Alleging Antitrust Violations				1
Loss Continency Other Complaints Alleging Antitrust Violations			31