Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 65,182	$ 61,555	$ 61,506	$ 57,852	$ 50,691	$ 51,459	$ 54,798	$ 52,238	$ 246,094	$ 209,185
Income from operations	4,030	4,939	4,620	3,635	2,698	3,800	3,837	3,126	17,223	13,461
Interest expense, net	(808)	(893)	(1,004)	(1,080)	(781)	(813)	(906)	(941)	(3,784)	(3,441)
Income before income taxes	3,222	4,046	3,616	2,555	1,917	2,987	2,931	2,185	13,439	10,020
Income tax expense	339	1,166	1,049	741	554	863	855	634	3,294	2,906
Net income	$ 2,883	$ 2,880	$ 2,567	$ 1,814	$ 1,363	$ 2,124	$ 2,076	$ 1,551	$ 10,145	$ 7,114
Basic (in dollars per share)	$ 0.23	$ 0.23	$ 0.20	$ 0.15	$ 0.11	$ 0.17	$ 0.17	$ 0.13	$ 0.81	$ 0.58
Diluted (in dollars per share)	$ 0.21	$ 0.21	$ 0.19	$ 0.13	$ 0.10	$ 0.16	$ 0.16	$ 0.12	$ 0.75	$ 0.54