Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares
Number of Shares
Outstanding at September 30, 2019 (in shares) | shares	1,686,902
Granted (in shares) | shares	92,610
Exercised (in shares) | shares	(184,849)
Canceled (in shares) | shares	(16,146)
Outstanding at March 31, 2020 (in shares) | shares	1,578,517	1,686,902
Weighted-Average Exercise Price
Outstanding at September 30, 2019 (in dollars per share) | $ / shares	$ 7.00
Granted (in dollars per share) | $ / shares	9.49
Exercised (in dollars per share) | $ / shares	3.49
Canceled (in dollars per share) | $ / shares	10.40
Outstanding at March 31, 2020 (in dollars per share) | $ / shares	$ 7.52	$ 7.00
Weighted-Average Remaining Contractual Term (in Years)
Outstanding	5 years 3 months 18 days	5 years 4 months 24 days
Outstanding, Aggregate Intrinsic Value | $	$ 2,557	$ 4,882
Vested and Expected to Vest at March 31, 2020
Outstanding (in shares) | shares	1,578,517
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 7.52
Weighted Average Remaining Contractual Term (in Years)	5 years 3 months 18 days
Aggregate Intrinsic Value (in thousands) | $	$ 2,557
Exercisable at March 31, 2020
Exercisable (in shares) | shares	1,124,765
Exercisable, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 6.76
Exercisable, Weighted Average Remaining Contractual Term (in Years)	3 years 10 months 24 days
Aggregate Intrinsic Value (in thousands) | $	$ 2,545