Inventories (Schedule of Major Classes of Inventory) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 78,319	$ 75,223
Work in progress	15,654	14,741
Finished goods and products held for resale	56,435	58,223
Costs of unbilled projects	3,438	2,347
Reserves for excess and obsolete	(11,467)	(13,370)
Inventory, Net	$ 142,379	$ 137,164