Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	May 31, 2020 USD ($) Swap loan	Sep. 23, 2016 EUR (€)
Derivative Instruments Gain Loss [Line Items]
Remaining unrecognized gains (losses) associated with derivative instruments included in AOCI	$ (18,056)		$ (18,056)		$ (26,506)
2016 Note Purchase Agreements [Member]
Derivative Instruments Gain Loss [Line Items]
Issuance date			Sep. 23, 2016
Face amount | €							€ 160,000,000
Series M Notes [Member]
Derivative Instruments Gain Loss [Line Items]
Face amount | €							€ 40,000,000
Maturity date			Sep. 23, 2026
Gain (Loss) on foreign currency transaction designated as a hedge of a net investment in a foreign subsidiary	673	$ 2,329	$ 1,744	$ (102)
2020 Fixed-Rate Cross-Currency Swaps [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	400,000		400,000			$ 400,000
2020 Fixed-Rate Cross-Currency Swaps [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, number of instruments | Swap						5
2020 Floating-Rate Cross-Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	$ 18,750		$ 18,750			$ 45,000
Fixed-Rate Cross Currency Interest Rate Contract [Member] | Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative, number of instruments | loan						5