EQUITY AND SHARE-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2014

EQUITY AND SHARE-BASED COMPENSATION

Schedule of assumptions used to determine the fair value of options as of the grant date

	Six months ended June 30, 2014	Six months ended June 30, 2013
	Black-Scholes	Black-Scholes	Binomial
Risk-free interest rate	1.80%	1.02% – 1.13%	0.01% – 2.02%
Expected stock price volatility	37.57%	36.35% – 36.76%	36.40% – 36.80%
Expected dividend yield	—	—	—
Expected option life (in years)	6.25	6.25	—
Contractual life (in years)	—	—	14
Fair value	$41.79	$31.33 – $35.77	$16.12 – $31.15

Summary of the weighted average fair value of stock options granted, the total intrinsic value of stock options exercised and the fair value of stock options vested

	Six months ended June 30,
(in thousands, except per share amounts)	2014		2013
Weighted average fair value at grant date per share	$	41.79	$	25.83
Intrinsic value of options exercised	4,124		9,625
Fair value of options vested	950		1,475

Summary of the activity of the entity's stock options

	Number of options		Weighted average exercise price		Weighted average contractual term (in years)	Aggregate intrinsic value (in thousands)
Outstanding at December 31, 2013	2,589,343		$	18.33	5.20	$	363,293
Granted	15,000		105.11
Exercised	(44,565	)	14.43
Forfeited	(16,001	)	73.14
Outstanding at June 30, 2014	2,543,777		18.56		4.71	244,590
Exercisable at June 30, 2014	2,216,285		13.28		4.35	224,515