Business Combinations - Pro Forma Results (unaudited) (Details) - IBA - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Revenue	$ 234,443	$ 228,117
Net income (loss)	$ 7,170	$ 2,464
Number of shares outstanding - basic (in shares)	12,282	12,018
Number of shares outstanding - diluted (in shares)	13,105	13,041
Basic earnings per share (loss) (in dollars per share)	$ 0.58	$ 0.21
Diluted earnings per share (loss) (in dollars per share)	$ 0.55	$ 0.19