Stock-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Summary of activities and changes in stock option plans
Number of Shares Outstanding at Beginning of Period	2,355
Weighted-Average Exercise Price Outstanding at Beginning of Period	$ 13.70
Number of Shares Granted	452
Weighted-Average Exercise Price Granted	$ 28.96
Number of Shares Exercised	(945)
Weighted-Average Exercise Price Exercised	$ 9.87
Number of Shares Forfeited	(64)
Weighted-Average Exercise Price Forfeited	$ 18.39
Number of Shares Expired	(9)
Weighted-Average Exercise Price Expired	$ 17.48
Number of Shares Outstanding at End of Period	1,789
Weighted-Average Exercise Price Outstanding at End of Period	$ 19.39
Weighted Average Remaining Contractual Term Outstanding at End of Period	7 years 4 months 28 days
Aggregate Intrinsic Value Outstanding at End of Period	$ 35,407
Number of Shares Exercisable at End of Period	986
Weighted-Average Exercise Price Exercisable at End of Period	$ 15.71
Weighted Average Remaining Contractual Term Exercisable at End of Period	6 years 3 months 25 days
Aggregate Intrinsic Value Exercisable at End of Period	23,145
Number of Shares Vested and Expected to Vest at End of Period	1,735
Weighted-Average Exercise Price Vested and Expected to Vest at End of Period	$ 19.20
Weighted Average Remaining Contractual Term Vested and Expected to Vest at End of Period	7 years 4 months 10 days
Aggregate Intrinsic Value Vested and Expected to Vest at End of Period	$ 34,680