Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 32,489	$ 36,131	$ 34,401	$ 30,215	$ 30,390	$ 29,256	$ 29,905	$ 26,111	$ 133,236	$ 115,662
Gross margin	7,885	8,338	7,448	6,532	7,253	6,385	6,401	5,811	30,202	25,850
Income from operations	2,819	2,614	2,204	1,146	2,149	1,753	1,839	889	8,782	6,630
Interest expense, net	(315)	(262)	(261)	(278)	(340)	(269)	(255)	(364)	(1,116)	(1,228)
Income before income taxes	2,504	2,352	1,943	868	1,809	1,484	1,584	525	7,666	5,402
Income tax expense	747	738	627	3,719	769	539	605	201	5,830	2,114
Net income	$ 1,757	$ 1,614	$ 1,316	$ (2,851)	$ 1,040	$ 945	$ 979	$ 324	$ 1,836	$ 3,288
Basic (in dollars per share)	$ 0.15	$ 0.14	$ 0.11	$ (0.24)	$ 0.09	$ 0.08	$ 0.09	$ 0.03	$ 0.15	$ 0.29
Diluted (in dollars per share)	$ 0.14	$ 0.13	$ 0.10	$ (0.24)	$ 0.08	$ 0.08	$ 0.08	$ 0.03	$ 0.14	$ 0.27
Write-down of deferred tax assets from revaluation of net operating losses due to change in federal tax rate									$ 3,400