Share Based Compensation (Tables)

6 Months Ended

Jun. 30, 2013

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,
	2013		2012		2013		2012
Stock options	$	2,631	$	2,349	$	5,502	$	4,626
Restricted stock		1,266		1,611		2,557		3,167
Stock-based compensation	$	3,897	$	3,960	$	8,059	$	7,793

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 June 30, 2013 (in thousands):

	Unrecognized Compensation Cost		Weighted Average Period of Expense Recognition (in Years)
Stock options	$	25,140		2.02
Restricted stock		4,947		0.94
Total	$	30,087

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, 2013 (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, 2012		6,565		$	22.17		2,666	$	14.71			$	206,636
Granted		150			68.22					$	19.25
Exercised		(661	)		18.44								41,550
Forfeited		(79	)		23.00
Outstanding at June 30, 2013		5,975		$	23.74		2,459	$	16.07			$	343,967
Expected to vest as of June 30, 2013		5,975		$	23.74

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, 2013 (shares in thousands):

	Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2012		472		$	28.98
Granted		36			58.02
Vested		(21	)		30.02
Cancelled		(25	)		29.99
Unvested at June 30, 2013		462		$	33.39

Stock Option [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 six months ended June 30, 2013, with the following weighted-average assumptions for grants during the period.

	Six Months Ended June 30,
	2013			2012
Risk-free interest rate		0.55	%		0.64	%
Dividend yield		—			—
Expected volatility		35.05	%		34.31	%
Expected life (in years)		4.0			4.0