EQUITY AND SHARE-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2013

EQUITY AND SHARE-BASED COMPENSATION

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

	Nine months endedSeptember 30, 2013		Nine months endedSeptember 30, 2012
	Black-Scholes	Binomial	Black-Scholes	Binomial
Risk-free interest rate	1.02% — 1.81%	0.01% — 2.71%	0.87% — 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 — $49.14	$16.12 — $41.72	$19.25 — $29.80	$9.98 — $22.76

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

	Nine months ended September 30,
(in thousands, except per share amounts)	2013		2012
Weighted average fair value at grant date per share	$	32.59	$	20.77
Intrinsic value of options exercised	24,587		11,535
Fair value of options vested	1,867		1,491

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	75,000		104.84
Exercised	(279,531	)	17.12
Forfeited	(117,248	)	59.49
Outstanding at September 30, 2013	2,736,530		18.34		5.4	332,955
Exercisable at September 30, 2013	2,216,347		11.99		4.9	283,735