COMMITMENTS AND CONTINGENCIES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Leased Office Space
Rental expense	$ 30,900,000	$ 17,700,000	$ 10,400,000
Minimum payments for operating leases having initial or remaining non-cancelable lease terms
2013	31,487,000
2014	32,070,000
2015	30,251,000
2016	26,185,000
2017	20,936,000
After 2017	78,100,000
Total	$ 219,029,000
Booking.com B.V. [Member]
Leased Office Space
Number of other countries with leased office space used to support international operations	43
Mauritius Company Limited (formerly known as Agoda)
Leased Office Space
Number of other countries with leased office space used to support international operations	22
Norwalk, Connecticut | Priceline.com Incorporated
Leased Office Space
Square feet of leased office space	70,000
Grand Rapids, Michigan | Priceline.com Incorporated
Leased Office Space
Square feet of leased office space	49,000
Cambridge, England | Booking.com Limited
Leased Office Space
Square feet of leased office space	32,000
Amsterdam, Netherlands | Booking.com B.V. [Member]
Leased Office Space
Square feet of leased office space	596,000
Bangkok, Thailand | Mauritius Company Limited (formerly known as Agoda)
Leased Office Space
Square feet of leased office space	102,000
Manchester, England | Rentalcars.com
Leased Office Space
Square feet of leased office space	29,000