Inventories - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Inventory Disclosure [Abstract]
Additional amount that would have been reported in inventory if FIFO method had been used	$ 8,286	$ 8,296
LIFO benefit	$ 10	75
Cost of goods sold		$ 340