EQUITY AND SHARE-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2013

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, 2013		Six months ended June 30, 2012
	Black-Scholes	Binomial	Black-Scholes	Binomial
Risk-free interest rate	1.02%–1.13%	0.01%–2.02%	0.97% – 1.17%	0.08% – 2.04%
Expected stock price volatility	36.35%–36.76%	36.40%–36.80%	34.22% – 34.65%	34.20% – 34.60%
Expected dividend yield	—	—	—	—
Expected option life (in years)	6.25	—	6.25	—
Contractual life (in years)	—	14	—	14
Fair value	$31.33–$35.77	$16.12–$31.15	$19.25 – $22.80	$11.65 – $17.27

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

	Six months ended June 30,
(in thousands, except per share amounts)	2013		2012
Weighted-average fair value at grant date per share	$	25.83	$	16.86
Intrinsic value of options exercised	9,625		8,339
Fair value of options vested	1,475		973

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, 2012	3,058,309		$	17.69	6.1	$	211,072
Granted	45,000		90.75
Exercised	(142,977	)	20.38
Forfeited	(102,875	)	62.27
Outstanding at June 30, 2013	2,857,457		17.09		5.5	220,622
Exercisable at June 30, 2013	2,320,557		11.89		5.1	191,243