Stock-based Compensation and Equity Grants - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Number of Shares
Outstanding at beginning of period (in shares)	2,226	2,324
Granted (in shares)	400	25
Cancelled (in shares)	(632)	(123)
Outstanding at end of period (in shares)	1,994	2,226	2,324
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 1.40	$ 1.40
Granted (in dollars per share)	5.94	2.80
Cancelled (in dollars per share)	1.28	1.40
Outstanding at end of period (in dollars per share)	$ 3.83	$ 1.40	$ 1.40
Share Based Compensation Arrangement by Share Based Payment, Award, Options Weighted Average Remaining Contractual Term [Abstract]
Outstanding	6 years 4 months 24 days	5 years 10 months 2 days	6 years 9 months 18 days
Share Based Compensation Arrangement by Share Based Payment, Award, Options Aggregate Intrinsic Value [Abstract]
Outstanding at the end of period (in dollars)	$ 8,489	$ 7,581	$ 3,649