Long-Term Debt - Narrative (Details)	9 Months Ended
	Jun. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Oct. 31, 2001 USD ($)
Line Of Credit Facility [Line Items]
Revolving credit facility borrowings, outstanding amount	$ 400,000	$ 800,000
U.S. Revolver
Line Of Credit Facility [Line Items]
Percentage of voting capital stock pledged as collateral	100.00%
Non-domestic subsidiaries of voting capital stock	65.00%
U.S. Revolver | Amended and Restated Credit Agreement
Line Of Credit Facility [Line Items]
Revolving credit facility	$ 75,000,000.0
Cash collateral pledged balance	30,000,000
Letters of credit collateral amount, minimum outstanding	0
Revolving credit facility borrowings, outstanding amount	0
Amount available under the credit facility	$ 35,100,000
Debt covenant, consolidated leverage ratio (less than)	3.0
Debt covenant, consolidated interest coverage ratio (greater than)	3.0
U.S. Revolver | Amended and Restated Credit Agreement | Fed Funds Rate
Line Of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
U.S. Revolver | Amended and Restated Credit Agreement | LIBOR
Line Of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
U.S. Revolver | Amended and Restated Credit Agreement | Base Rate | Minimum
Line Of Credit Facility [Line Items]
Basis spread on variable rate	(0.25%)
U.S. Revolver | Amended and Restated Credit Agreement | Base Rate | Maximum
Line Of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
U.S. Revolver | Amended and Restated Credit Agreement | Financial Standby Letter of Credit
Line Of Credit Facility [Line Items]
Guarantee liability	$ 39,900,000
Industrial Development Revenue Bonds
Line Of Credit Facility [Line Items]
Borrowings			$ 8,000,000.0
Interest rate	0.13%