STOCK-BASED EMPLOYEE COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2013

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 six months ended June 30, 2013: 

Share-Based Awards	Shares		Weighted Average Grant Date Fair Value
Unvested at December 31, 2012	540,128		$	389.21
Granted	152,630		$	708.32
Vested	(254,548	)	$	239.15
Performance Share Units Adjustment	12,949		$	670.17
Forfeited	(9,143	)	$	526.24
Unvested at June 30, 2013	442,016		$	591.22

KAYAK [Member]

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

Schedule of share-based compensation, stock options, activity

The following table summarizes for the three months ended June 30, 2013 stock option activity for vested and unvested employee stock options assumed in the acquisition of KAYAK:

Assumed Stock Options	Number of Shares		Weighted Average Exercise Price		Aggregate Intrinsic Value(000's)		Weighted Average Remaining Contractual Term (in years)
Balance, May 21, 2013	540,179		$	260.96	$	314,133	6.8
Exercised	(329,687	)	$	207.93
Forfeited	(2,210	)	$	395.99
Balance, June 30, 2013	208,282		$	343.47	$	100,641	7.5
Vested and exercisable as of June 30, 2013	94,990		$	217.30	$	57,884	6.1
Vested and exercisable as of June 30, 2013 and expected to vest thereafter, net of estimated forfeitures	202,905		$	340.14	$	98,719	7.4

Schedule of share-based compensation, stock options, valuation assumptions

The following assumptions were used to determine fair value:

	Weighted Average		Range
Risk-free interest rate	0.23	%	0.11% - 0.63%
Expected volatility	32	%	25% - 39%
Expected life (in years)	2.2		9 months - 4 years
Dividend yield	—	%	—	%