Discontinued Operations and Disposals - Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Reversal of) provision for allowance for doubtful accounts, net	$ 44	$ 24	$ 1,074
(Loss) gain on sale of subsidiary		(13,709)	1,614
Tempress and SoLayTec \| Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations, net of tax		(11,816)	(8,297)
Depreciation and amortization		180	562
(Reversal of) provision for allowance for doubtful accounts, net		(62)	874
(Loss) gain on sale of subsidiary		(10,916)	1,614
Purchases of property, plant and equipment		$ 1	$ 131

Amount of deprecation and amortization expense attributable to property, plant and equipment and intangible assets of discontinued operations.

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Amount of cash outflow from the acquisition of or improvements to long-lived, physical assets used to produce goods and services and not intended for resale, classified as other.

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