Inventories - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Inventory Disclosure [Abstract]
Proceeds from federal relief grants	$ 4,136,000	$ 4,466,000	$ 4,629,000	$ 15,597,000