Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2013

Presented below is a summary of our stock option activity for the three months ended March 31, 2013 (shares in thousands):

	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms	Aggregate Intrinsic Value

Outstanding at December 31, 2012	4,604		$	14.11
Granted	3		$	28.74
Exercised	(514	)	$	10.46
Forfeited	(121	)	$	22.28
Expired	(1	)	$	5.81
Outstanding at March 31, 2013	3,971		$	14.24	4.51	$	53,419
Expected to vest at March 31, 2013	1,502		$	22.98	6.26	$	7,261
Exercisable at March 31, 2013	2,429		$	8.55	3.27	$	45,970

Schedule of assumptions used for estimating fair value of options granted

	Three months ended March 31,
	2013		2012
Expected dividend yield	—		—
Risk-free interest rate	0.67	%	—
Expected volatility	40.05	%	—
Expected life	4.47 years		—

Summary of status of restricted stock units

A summary of the status of our restricted stock units as of March 31, 2013 and of changes in restricted stock units outstanding under the 2006 Stock Plan, as amended, for the three months ended March 31, 2013 is as follows (in thousands, except for weighted average grant date fair value per unit):

	Number of Units		Weighted Average Grant Date Fair Value per Unit		Aggregate Intrinsic Value
Outstanding balance at December 31, 2012	237		$	25.44
Granted	197		$	28.74
Vesting of restricted stock units, net of shares withheld for taxes	(35	)	$	24.87
Shares withheld for taxes	(20	)	$	24.87
Forfeitures	(29	)	$	24.79
Outstanding balance at March 31, 2013	350		$	26.62	$	9,495

Summary of status of restricted stock awards

A summary of the status of our restricted stock awards at March 31, 2013 and of changes in restricted stock awards outstanding under the 2006 Stock Plan for the three months ended March 31, 2013 is as follows (in thousands, except for weighted average grant date fair value):

	Shares		Weighted Average Grant Date Fair Value per Share		Aggregate Intrinsic Value
Outstanding balance at December 31, 2012	192		$	10.42
Granted	—		—
Vesting of restricted stock awards	(61	)	$	10.42
Shares withheld for payment of taxes upon vesting of restricted stock awards	(35	)	$	10.42
Forfeitures	(14	)	$	10.42
Outstanding balance at March 31, 2013	82		$	10.42	$	2,214