Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2012

Stock-based Compensation [Abstract]

Summary of stock-based compensation expense recognized by the company

	Three Months Ended June 30,				Six Months Ended June 30,
	2012		2011		2012		2011
Stock options	$	1,673	$	433	$	3,062	$	934
Restricted stock awards		—		19		—		42
Restricted stock units		2,108		1,449		3,910		2,027
Total recognized stock-based compensation expense	$	3,781	$	1,901	$	6,972	$	3,003

Summary of information related to stock options

	Number of Options Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Balance, December 31, 2011		1,682,911		$	11.82
Granted		258,600
Exercised		(376,211	)
Forfeited		(78,958	)
Balance, June 30, 2012		1,486,342		$	17.25		7.91	$	22,443,987
Vested at June 30, 2012		714,097		$	4.76		6.90	$	17,522,120
Exercisable at June 30, 2012		752,556		$	4.64		6.84	$	18,295,189

Summary of activity for restricted stock units

	Number  of RSUs			Weighted Average Grant Date Fair Value
Balance, December 31, 2011		367,315		$	27.17
Granted		399,262			33.87
Vested		(150,802	)		23.04
Forfeited		(39,608	)		34.71
Balance, June 30, 2012		576,167		$	32.49