Stock-Based Compensation - Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2017
Stock options activity
Outstanding, beginning of period (in shares)	1,353,558
Granted (in shares)	386,556
Exercised (in shares)	(103,334)
Cancelled / Forfeited (in shares)	(33,563)
Outstanding, end of period (in shares)	1,603,217	1,353,558
Vested and exercisable, end of period (in shares)	878,023
Vested and expected to vest, end of period (in shares)	1,527,998
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 37.98
Granted (in dollars per share)	63.24
Exercised (in dollars per share)	34.29
Cancelled / Forfeited (in dollars per share)	50.54
Outstanding, end of period (in dollars per share)	44.05	$ 37.98
Vested and exercisable, end of period (in dollars per share)	36.56
Vested and expected to vest, end of period (in dollars per share)	$ 43.58
Weighted Average Remaining Contractual Term
Outstanding, end of period	7 years 6 months 16 days	7 years 3 months 17 days
Vested and exercisable, end of period	6 years 5 months 3 days
Vested and expected to vest, end of period	7 years 5 months 21 days
Aggregate Intrinsic Value
Outstanding, end of period	$ 35,522	$ 23,535
Vested and exercisable, end of period	26,023
Vested and expected to vest, end of period	$ 34,563