Equity Option Award Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Option Activity [Abstract]
Number of options, Outstanding at January 1, 2013	2,210,116
Number of options, Granted	551,480
Number of options, Exercised	(244,519)
Number of options, Forfeited	(81,446)
Number of options, Expired	(3,841)
Number of options, Outstanding at December 31, 2013	2,431,790
Number of options, Vested or expected to vest at December 31, 2013	2,378,775
Number of options, Exercisable at December 31, 2013	797,724
Weighted-average exercise price, Outstanding at January 1, 2013	$ 25.35
Weighted-average exercise price, Granted	$ 46.99
Weighted-average exercise price, Exercised	$ 15.11
Weighted-average exercise price, Forfeited	$ 34.66
Weighted-average exercise price, Expired	$ 21.15
Weighted-average exercise price, Outstanding at December 31, 2013	$ 30.98
Weighted-average exercise price, Vested or expected to vest at December 31, 2013	$ 30.77
Weighted-average exercise price, Exercisable at December 31, 2013	$ 18.92
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2013	4 years 11 months 7 days
Weighted-Average Remaining Contractual Term, Vested or expected to vest at December 31, 2013	4 years 11 months 3 days
Weighted-Average Remaining Contractual Term, Exercisable at December 31, 2013	3 years 7 months 17 days
Aggregate intrinsic value, Outstanding at December 31, 2013	$ 79,528	[1]
Aggregate intrinsic value, Vested or expected to vest at December 31, 2013	78,305	[1]
Aggregate intrinsic value, Exercisable at December 31, 2013	$ 35,717	[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.