Acquisitions - Proforma Information (Details) - Bajio - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Revenue	$ 748,957	$ 854,926
Net income (loss)	$ 8,828	$ (65,206)
Basic earnings (loss) per common share (in dollars per share)	$ 0.16	$ (1.18)
Diluted earnings (loss) per common share (in dollars per share)	$ 0.16	$ (1.18)