SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning of Year	$ 2,377	$ 1,900	$ 1,747
Amount of Charge (Benefit) To Expenses	(1,122)	432	185
Deductions and Adjustments	(672)	45	(32)
Balance At End of Year	583	2,377	1,900
Valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning of Year	2,565	133	2,271
Amount of Charge (Benefit) To Expenses	658	2,432	0
Deductions and Adjustments	(275)	0	(2,138)
Balance At End of Year	$ 2,948	$ 2,565	$ 133