STOCK-BASED COMPENSATION (Narrative) (Details) (USD $)	12 Months Ended			7 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 186,425,000	$ 140,526,000	$ 71,565,000
Share-based compensation, cumulative charges for adjustment of the estimated probable outcome on unvested performance awards	20,600,000	24,100,000	900,000
Stock-based compensation cost, non-employee directors	2,300,000	2,100,000	1,800,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	38,400,000	18,500,000	7,600,000
Exercised (in shares)	(7,780)
Exercised (in dollars per share)	$ 22.47
Balance, (in shares)	1,220
Weighted Average Exercise Price (in dollars per share)	$ 23.08
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	6 months
Aggregate intrinsic value	1,400,000
Stock options exercised, total intrinsic value	9,300,000	44,900,000	75,200,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant term (in years)	10 years
Awards Other Than Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units and performance share units aggregate grant-date fair value	168,100,000	118,600,000	61,100,000	118,600,000
Aggregate grant-date fair value of restricted shares, performance share units and restricted stock units vested during the period	96,300,000	62,600,000	38,300,000
Total future compensation cost related to unvested share-based awards	263,800,000
Total future compensation cost related to unvested share-based awards, expected period of recognition	1 year 8 months
Granted (in shares)	128,484	162,341	95,062
Granted (in dollars per share)	$ 1,308.13	$ 730.47	$ 643.12
Unvested at (in shares)	570,315.000000	534,319.000000	540,128.000000	534,319.000000	799,980
Performance Share Units 2014 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	72,277
Grant date fair value	96,100,000
Granted (in dollars per share)	$ 1,329.11
Unvested at (in shares)	72,098
Estimated number of probable shares to be issued (in shares)	109,618
Maximum shares that could be issued (in shares)	145,981
Minimum shares that could be issued (in shares)	50,884
Performance Share Units 2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		104,865
Grant date fair value		74,400,000
Granted (in dollars per share)		$ 709.74
Unvested at (in shares)	102,816
Estimated number of probable shares to be issued (in shares)	197,225
Maximum shares that could be issued (in shares)	225,202
Minimum shares that could be issued (in shares)	40,120
Performance Share Units 2012 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			60,365
Grant date fair value			39,000,000
Granted (in dollars per share)			$ 645.86
Unvested at (in shares)	57,571
Estimated number of probable shares to be issued (in shares)	100,190
1999 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to be issued under the plan (in shares)	2,650,485
KAYAK 2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to be issued under the plan (in shares)	14,351
Buuteeq, Inc. Amended and Restated 2010 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to be issued under the plan (in shares)	191
OpenTable 2009 Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to be issued under the plan (in shares)	238,804
Minimum | Awards Other Than Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Maximum | Awards Other Than Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
Assumed in an acquisition | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	24,700,000			30,900,000
Total future compensation cost related to unvested share-based awards, expected period of recognition	1 year 7 months
Stock-based compensation expense, not yet recognized	36,200,000
Exercised (in shares)	(43,223)	(387,669)
Exercised (in dollars per share)	$ 342.39	$ 222.73
Balance, (in shares)	145,165.000	128,708.000	0	128,708.000
Weighted Average Exercise Price (in dollars per share)	$ 383.05	$ 335.83	$ 0	$ 335.83
Weighted Average Remaining Contractual Term	5 years 8 months
Aggregate intrinsic value	109,914,000	106,386,000	0	106,386,000
Stock options exercised, total intrinsic value	39,900,000			236,900,000
Acquisition date fair value of assumed options	45,500,000
Acquisition date fair value per share of assumed stock options	$ 734.76
Assumed unvested employee stock options vesting during period (in shares)	41,524			65,293
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 24,200,000			$ 30,900,000