Acquisitions and Divestitures (WCSI Acquisition) (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 01, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Cash paid to acquire assets		$ 229,277	$ 21,037	$ 13,108
Goodwill		473,572	407,376	$ 397,205
Water consulting specialists, inc
Business Acquisition [Line Items]
Cash paid to acquire assets	$ 12,025
Contingent consideration, liability	761	150
Cash from previous acquisition		$ 21
Acquisition costs			$ 83
Current assets	1,813
Property, plant, and equipment	221
Goodwill	4,340
Identifiable assets, net	7,336
Other non-current assets	86
Total assets acquired	13,796
Liabilities assumed	(1,792)
Net assets acquired	$ 12,004