Stock-Based Compensation - Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Number of Options
Outstanding at December 31, 2015 | shares	648
Granted | shares	244
Exercised | shares	(77)
Forfeited/canceled/expired | shares	0
Outstanding at March 31, 2016 | shares	815
Vested and expected to vest at March 31, 2016 | shares	814
Exercisable on September 30, 2015 | shares	469
Weighted-Average Exercise Price
Outstanding at December 31, 2015 | $ / shares	$ 30.50
Granted | $ / shares	49.67
Exercised | $ / shares	25.25
Forfeited/canceled/expired | $ / shares	0.00
Outstanding at March 31, 2016 | $ / shares	36.72
Vested and expected to vest at March 31, 2016 | $ / shares	36.72
Exercisable on March 31, 2016 | $ / shares	$ 27.15
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Outstanding at December 31, 2015	5 years 4 months 9 days
Vested and expected to vest at March 31, 2016	5 years 4 months 9 days
Exercisable on March 31, 2016	4 years 6 months 25 days
Exercised | $	$ 2,415
Outstanding at March 31, 2016 | $	20,847	[1]
Vested and expected to vest at March 31, 2016 | $	20,840	[1]
Exercisable on March 31, 2016 | $	$ 16,422	[1]

[1] The aggregate intrinsic value represents the total pre-tax value (the difference between our closing stock price on the last trading day of the first quarter of 2016 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had they all exercised their options on March 31, 2016. This amount will change based on the fair market value of our stock.