Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 81,917	$ 78,319
Work in progress	16,956	15,654
Finished goods and products held for resale	63,339	56,435
Costs of unbilled projects	3,860	3,438
Reserves for excess and obsolete	(11,046)	(11,467)
Inventory, Net	$ 155,026	$ 142,379