Stock-Based Compensation - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Weighted-average grant date fair value per share
Stock-based compensation expense	$ 12,919	$ 8,129	$ 34,064	$ 17,510
Restricted Stock Units
Shares
Unvested restricted at the beginning of the period (in shares)			60,000
Granted (in shares)			638,673
Vested (in shares)			(15,000)
Forfeited (in shares)			(17,600)
Unvested restricted at the end of the period (in shares)	666,073		666,073
Weighted-average grant date fair value per share
Unvested restricted at the beginning of the period (in dollars per share)			$ 56.00
Granted (in dollars per share)			49.64
Vested (in dollars per share)			56.00
Forfeited (in dollars per share)			43.39
Unvested restricted at the end of the period (in dollars per share)	$ 50.23		$ 50.23
Unrecognized compensation costs	$ 28,600		$ 28,600
Weighted average period over which unrecognized compensation costs are expected to be recognized			3 years 4 months 24 days
Stock-based compensation expense	$ 200		$ 200
PBRSUs
Shares
Granted (in shares)			15,000
Vested (in shares)	0		0