STOCK-BASED EMPLOYEE COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Activity of unvested restricted stock units and performance share units

Restricted Stock Units and Performance Share Units

The following table summarizes the activity of restricted stock units and performance share units ("share-based awards") during the nine months ended September 30, 2017: 

Share-Based Awards	Shares		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2016	515,606			$	1,287.88
Granted	166,957			$	1,742.75
Vested	(136,344	)		$	1,314.49
Performance Share Units Adjustment	6,702			$	1,274.19
Forfeited	(32,081	)		$	1,402.11
Unvested at September 30, 2017	520,840			$	1,420.00

Schedule of share-based compensation, stock options, activity

Stock Options

All outstanding employee stock options were assumed in acquisitions. The following table summarizes the activity for stock options during the nine months ended September 30, 2017: 

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, 2016	48,983			$	372.07		$	53,587	4.4
Exercised	(14,236	)		$	301.68
Forfeited	(948	)		$	837.90
Balance, September 30, 2017	33,799			$	388.65		$	48,744	4.0
Vested and exercisable as of September 30, 2017	33,400			$	383.56		$	48,338	4.0
Vested and exercisable as of September 30, 2017 and expected to vest thereafter	33,799			$	388.65		$	48,744	4.0