Share Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

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 six month periods ended June 30 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Stock options	$	2,889	$	2,631	$	6,300	$	5,502
Restricted stock		4,798		1,266		11,999		2,557
Stock-based compensation	$	7,687	$	3,897	$	18,299	$	8,059

Summary of Total Unrecognized Compensation Related to Stock-Based Compensation

The following table summarizes the Company’s total unrecognized compensation related to stock-based compensation as of June 30, 2014 (in thousands):

	Unrecognized Compensation Cost		Weighted Average Period of Expense Recognition (in Years)
Stock options	$	20,496		1.90
Restricted stock		14,580		0.97
Total	$	35,076

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 six month period ended June 30, 2014 (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, 2013		5,331		$	25.68		2,589	$	16.57			$	487,673
Granted		237			108.29					$	31.45
Exercised		(483	)		17.23								55,356
Forfeited		(170	)		49.49
Outstanding at June 30, 2014		4,915		$	29.45		2,438	$	19.42			$	502,986
Expected to vest as of June 30, 2014		4,915		$	29.45

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 six months ended June 30, 2014 (shares in thousands):

	Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2013		634		$	67.83
Granted		39			107.09
Vested		(120	)		89.22
Cancelled		(10	)		35.78
Unvested at June 30, 2014		543		$	66.54

Stock Options [Member]

Schedule of Weighted-Average Assumptions

The fair value of stock option awards granted was estimated using the Black-Scholes option pricing model during the three months ended June 30, 2014 and 2013, with the following weighted-average assumptions for grants during the period.

	June 30
	2014			2013
Risk-free interest rate		0.90	%		0.55	%
Dividend yield		—			—
Expected volatility		34.92	%		35.05	%
Expected life (in years)		3.8			4.0