Quarterly Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Unaudited quarterly consolidated statement of operations
Revenue	$ 55,890	$ 47,722	$ 52,824	$ 49,504	$ 58,790	$ 56,882	$ 56,800	$ 54,053	$ 205,940	$ 226,525	$ 224,514
Gross profit	33,163	25,228	26,205	25,328	29,038	28,551	29,218	26,473	109,924	113,280	109,712
Income (loss) before provision for income taxes	5,538	422	(4,195)	(4,738)	(5,163)	(4,107)	(4,034)	(4,756)	(2,973)	(18,060)	(20,943)
Net loss	$ 5,447	$ 213	$ (4,238)	$ (5,196)	$ (5,227)	$ (4,649)	$ (4,362)	$ (5,022)	$ (3,774)	$ (19,260)	$ (11,615)
Unaudited quarterly consolidated statement of operations
Basic income (loss) per common share (in dollars per share)	$ 0.16	$ 0.01	$ (0.13)	$ (0.15)	$ (0.16)	$ (0.14)	$ (0.13)	$ (0.15)
Diluted income (loss) per common share (in usd per share)	$ 0.16	$ 0.01	$ (0.13)	$ (0.15)	$ (0.16)	$ (0.14)	$ (0.13)	$ (0.15)
Basic and diluted weighted average shares outstanding (in shares)	33,584,040	33,695,936	33,624,889	33,545,235	33,291,275	33,164,750	32,987,608	32,808,144
Diluted weighted average shares outstanding (in shares)	33,986,862	33,815,332	33,624,889	33,545,235	33,291,275	33,164,750	32,987,608	32,808,144