Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 82,065	$ 78,319
Work in progress	19,497	15,654
Finished goods and products held for resale	61,918	56,435
Costs of unbilled projects	4,143	3,438
Reserves for excess and obsolete	(10,836)	(11,467)
Inventory, Net	$ 156,787	$ 142,379