Stock-Based Compensation (Weighted Average Grant Date Fair Value) (Details) (Common Stock, USD $)	9 Months Ended
	Sep. 30, 2013
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at January 1, 2013 (shares)	3,263,830
Granted (shares)	684,980
Exercised (shares)	(486,837)
Canceled (shares)	(61,512)
Options outstanding at September 30, 2013	3,400,461
Options exercisable at September 30, 2013	1,759,856
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding at January 1, 2013, Weighted Average Exercise Price	$ 7.02
Granted, Weighted Average Exercise Price	$ 18.09
Exercised, Weighted Average Exercise Price	$ 5.98
Canceled, Weighted Average Exercise Price	$ 10.41
Options outstanding at September 30, 2013, Weighted Average Exercise Price	$ 9.34
Options exercisable at September 30, 2013, Weighted Average Exercise Price	$ 6.52
Options outstanding at September 30, 2013, Weighted Average Remaining Contractual Term (In Years)	7 years 2 months 27 days
Options exercisable at September 30, 2013, Weighted Average Remaining Contractual Term	5 years 9 months
Options outstanding at September 30, 2013, Aggregate Intrinsic Value	$ 26,319,147
Options exercisable at September 30, 2013, Aggregate Intrinsic Value	$ 18,086,044