STOCK-BASED EMPLOYEE COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2014

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Activity of unvested restricted stock units and performance share units

Restricted Stock Units and Performance Share Units

The following table summarizes the activity of unvested restricted stock units and performance share units ("share-based awards") during the three months ended March 31, 2014: 

Share-Based Awards	Shares		Weighted Average Grant Date Fair Value
Unvested at December 31, 2013	534,319			$	615.10
Granted	95,476			$	1,338.24
Vested	(180,616	)		$	469.32
Performance Share Units Adjustment	25,822			$	800.59
Forfeited	(1,438	)		$	838.94
Unvested at March 31, 2014	473,563			$	825.92

KAYAK [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of share-based compensation, stock options, activity

Employee Stock Options Assumed in the Acquisition of KAYAK

The Company assumed vested and unvested employee stock options as part of the acquisition of KAYAK on May 21, 2013. The following table summarizes the activity of employee stock options assumed in the acquisition of KAYAK during the three months ended March 31, 2014: 

Assumed Employee Stock Options	Number of Shares		Weighted Average  Exercise Price			Aggregate  Intrinsic Value (in thousands)			Weighted Average Remaining Contractual Term (in years)
Balance, December 31, 2013	128,708			$	335.83		$	106,386	6.9
Exercised	(23,809	)		$	313.57
Forfeited	(147	)		$	452.45
Balance, March 31, 2014	104,752			$	340.73		$	89,161	6.7
Vested and exercisable as of March 31, 2014	72,009			$	268.68		$	66,479	6.0
Vested and exercisable as of March 31, 2014 and expected to vest thereafter, net of estimated forfeitures	103,203			$	337.72		$	88,153	6.7