Equity Option Award Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Option Activity [Abstract]
Number of options, Outstanding at January 1, 2014	2,431,790
Number of options, Granted	700,018
Number of options, Exercised	(154,830)
Number of options, Forfeited	(60,525)
Number of options, Expired	(6,344)
Number of options, Outstanding at December 31, 2014	2,910,109
Number of options, Vested or expected to vest at December 31, 2014	2,856,031
Number of options, Exercisable at December 31, 2014	985,033
Weighted-average exercise price, Outstanding at January 1, 2014	$ 30.98
Weighted-average exercise price, Granted	$ 69.06
Weighted-average exercise price, Exercised	$ 23.02
Weighted-average exercise price, Forfeited	$ 49.34
Weighted-average exercise price, Expired	$ 29.18
Weighted-average exercise price, Outstanding at December 31, 2014	$ 40.19
Weighted-average exercise price, Vested or expected to vest at December 31, 2014	$ 39.81
Weighted-average exercise price, Exercisable at December 31, 2014	$ 23.96
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2014	4 years 6 months 20 days
Weighted-Average Remaining Contractual Term, Vested or expected to vest at December 31, 2014	4 years 6 months 8 days
Weighted-Average Remaining Contractual Term, Exercisable at December 31, 2014	3 years 1 month 17 days
Aggregate intrinsic value, Outstanding at December 31, 2014	$ 45,492	[1]
Aggregate intrinsic value, Vested or expected to vest at December 31, 2014	45,323	[1]
Aggregate intrinsic value, Exercisable at December 31, 2014	$ 27,463	[1]

[1] The aggregate intrinsic value is based upon the difference between the Company’s closing stock price at the date of the Consolidated Balance Sheet and the exercise price of the stock option for in-the-money stock options. The intrinsic value of outstanding stock options fluctuates based upon the trading value of the Company’s Common stock.