Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used to Estimate Fair Value of Stock Options

The following assumptions were used to estimate the fair value of options granted using the Black-Scholes option-pricing model:

	For the three months ended March 31,
	2013	2012
Risk free interest rate	0.60% - 0.81%		0.62% - 0.83%
Dividend yield	0.0%		0.0%
Expected volatility	25.0% - 29.0%		53.0%
Expected lives	3.9 – 4.8 years		3.8 – 4.6 years

Company's Activities with Respect to its Stock Options

The following table summarizes the Company’s activities with respect to its stock options for the three months ended March 31, 2013:

	Number of Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)
	(in thousands)
Outstanding at December 31, 2012		2,831		$	34.06
Granted		935		$	72.99
Exercised		(193	)	$	30.61
Canceled		(26	)	$	43.29
Outstanding at March 31, 2013		3,547		$	44.44		4.67
Exercisable at March 31, 2013		1,746		$	29.56		3.12
Unvested at March 31, 2013		1,801		$	58.86		6.18

Company's Restricted Stock Unit Activity

The following table summarizes the Company’s restricted stock unit activity for the three months ended March 31, 2013:

	Number of Units			Weighted- Average Grant Date Fair Value per share
	(in thousands)
Outstanding at December 31, 2012		294		$	43.27
Granted		111			72.99
Restriction Lapse		(87	)		42.19
Forfeited/Canceled		(6	)		43.17
Outstanding at March 31, 2013		312		$	54.12