Credit Facilities, Short-term Borrowings and Long-term Debt (Narrative) (Details)	6 Months Ended
	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	May 31, 2018 USD ($)	Sep. 23, 2016 EUR (€)	Oct. 01, 2013 USD ($)
Debt Instrument [Line Items]
Balance of unamortized debt issuance costs	$ 2,299,000	$ 2,478,000
Short-term borrowings	100,000,000	220,000,000
The Notes [Member]
Debt Instrument [Line Items]
Balance of unamortized debt issuance costs	$ 2,299,000	2,478,000
2013 Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Face amount					$ 250,000,000
2016 Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Issuance date	Sep. 23, 2016
Face amount | €				€ 160,000,000
Series M Notes [Member]
Debt Instrument [Line Items]
Face amount | €				40,000,000
Series N Notes [Member]
Debt Instrument [Line Items]
Face amount | €				77,000,000
Series O Notes [Member]
Debt Instrument [Line Items]
Face amount | €				€ 43,000,000
2018 Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Face amount			$ 400,000,000
Series P Notes [Member]
Debt Instrument [Line Items]
Face amount		85,000,000	85,000,000
Series Q Notes [Member]
Debt Instrument [Line Items]
Face amount			85,000,000
Series R Notes [Member]
Debt Instrument [Line Items]
Face amount			75,000,000
Series S Notes [Member]
Debt Instrument [Line Items]
Face amount			75,000,000
Series T Notes [Member]
Debt Instrument [Line Items]
Face amount			$ 80,000,000
Notes Payable to Banks [Member] | Series J Notes [Member]
Debt Instrument [Line Items]
Maturity date	Nov. 15, 2020
Effective interest rate	2.94%
Notes Payable to Banks [Member] | Series J Notes [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
Notes Payable to Banks [Member] | Series M Notes [Member]
Debt Instrument [Line Items]
Maturity date	Sep. 23, 2026
Notes Payable to Banks [Member] | Series N Notes [Member]
Debt Instrument [Line Items]
Maturity date	Sep. 23, 2028
Notes Payable to Banks [Member] | Series O Notes [Member]
Debt Instrument [Line Items]
Maturity date	Sep. 23, 2031
Notes Payable to Banks [Member] | Series P Notes [Member]
Debt Instrument [Line Items]
Maturity date	May 30, 2025
Notes Payable to Banks [Member] | Series Q Notes [Member]
Debt Instrument [Line Items]
Maturity date	May 30, 2027
Notes Payable to Banks [Member] | Series R Notes [Member]
Debt Instrument [Line Items]
Maturity date	May 30, 2029
Notes Payable to Banks [Member] | Series S Notes [Member]
Debt Instrument [Line Items]
Maturity date	May 30, 2030
Notes Payable to Banks [Member] | Series T Notes [Member]
Debt Instrument [Line Items]
Maturity date	May 30, 2033
Foreign Lines of Credit And Overdraft Facilities [Member]
Debt Instrument [Line Items]
Short-term borrowings	$ 0	0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date	Jun. 19, 2024
Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.875%
Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Balance of unamortized debt issuance costs, line of credit	$ 2,541,000	$ 2,840,000
Cross Currency Interest Rate Swaps [Member] | Series P Notes [Member]
Debt Instrument [Line Items]
Effective interest rate	1.82%
Cross Currency Interest Rate Swaps [Member] | Series Q Notes [Member]
Debt Instrument [Line Items]
Effective interest rate	2.15%
Cross Currency Interest Rate Swaps [Member] | Series R Notes [Member]
Debt Instrument [Line Items]
Effective interest rate	2.42%
Cross Currency Interest Rate Swaps [Member] | Series S Notes [Member]
Debt Instrument [Line Items]
Effective interest rate	2.55%
Cross Currency Interest Rate Swaps [Member] | Series T Notes [Member]
Debt Instrument [Line Items]
Effective interest rate	2.90%