Share Based Compensation (Tables)

3 Months Ended

Mar. 31, 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 month periods ended March 31 (in thousands):

	Three Months Ended March 31,
	2013		2012
Stock options	$	2,871	$	2,277
Restricted stock		1,291		1,557
Stock-based compensation	$	4,162	$	3,834

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 March 31, 2013 (in thousands):

	Unrecognized Compensation Cost		Weighted Average Period  of Expense Recognition (in Years)
Stock options	$	26,535		2.25
Restricted stock		6,213		1.19
Total	$	32,748

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 three month period ended March 31, 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		60			58.02					$	16.29
Exercised		(298	)		18.20								17,404
Outstanding at March 31, 2013		6,327		$	22.70		2,476	$	14.42			$	341,471
Expected to vest as of March 31, 2013		6,327		$	22.70

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 three months ended March 31, 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 March 31, 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 three months ended March 31, 2013, with the following weighted-average assumptions for grants during the period.

Risk-free interest rate	0.57	%
Dividend yield	—
Expected volatility	34.84	%
Expected life (in years)	4.0