Share Based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

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

Summary of Expense Related to Share-Based Payments

The table below summarizes the expense recognized related to share-based payments recognized for the three and nine month periods ended September 30 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Stock options	$	4,348	$	3,207	$	13,190	$	9,507
Restricted stock		9,539		4,786		31,197		16,785
Stock-based compensation	$	13,887	$	7,993	$	44,387	$	26,292

Summary of Total Unrecognized Compensation Cost Related to Stock-Based Compensation

The following table summarizes the Company’s total unrecognized compensation cost related to stock-based compensation as of September 30, 2015 (in thousands):

	Unrecognized Compensation Cost		Weighted Average Period of Expense Recognition (in Years)
Stock options	$	72,976		1.74
Restricted stock		13,198		0.82
Total	$	86,174

Summary of Changes in Number of Shares of Common Stock Under Option

The following summarizes the changes in the number of shares of common stock under option for the nine month period ended September 30, 2015 (shares and aggregate intrinsic value in thousands):

	Shares			Weighted Average Exercise Price		Options Exercisable at End of Period		Weighted Average Exercise Price of Exercisable Options		Weighted Average Fair Value of Options Granted During the Period		Aggregate Intrinsic Value
Outstanding at December 31, 2014		5,131		$	58.71		2,370	$	21.75			$	461,770
Granted		575			155.69					$	35.89
Exercised		(477	)		29.31								51,624
Forfeited		(112	)		106.66
Outstanding at September 30, 2015		5,117		$	71.30		2,578	$	26.49			$	339,387
Expected to vest as of September 30, 2015		5,117		$	71.30

Schedule of Weighted-Average Assumptions

The fair value of stock option awards granted was estimated using the Black-Scholes option pricing model during the nine months ended September 30, 2015 and 2014, with the following weighted-average assumptions for grants during the period:

	September 30
	2015			2014
Risk-free interest rate		1.27	%		1.10	%
Dividend yield		—			—
Expected volatility		27.71	%		34.76	%
Expected life (in years)		3.8			3.8

Summary of Changes in Number of Shares of Restricted Stock and Restricted Stock Units

The following table summarizes the changes in the number of shares of restricted stock and restricted stock units for the nine months ended September 30, 2015 (shares in thousands):

	Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2014		716		$	121.38
Granted		124			149.72
Vested		(183	)		77.59
Cancelled		(50	)		133.94
Unvested at September 30, 2015		607		$	138.89