Impairment - Wood Treatment - Long-lived Asset Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Long-lived asset impairment charges:
Property, plant, and equipment, net	$ 230,392	$ 2,314	$ 67,372
Goodwill	227,126
Total wood treatment impairment charges	230,392	2,314	67,372
Wood treatment
Long-lived asset impairment charges:
Property, plant, and equipment, net	91	450	4,063
Other intangible assets, net	3,175	1,864	63,309
Total wood treatment long-lived asset impairment charges	3,266	2,314	67,372
Goodwill	25,576	0	0
Total wood treatment impairment charges	$ 28,842	$ 2,314	$ 67,372