Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	May 31, 2020 USD ($) Loan Swap	Sep. 23, 2016 EUR (€)
Derivative Instruments Gain Loss [Line Items]
Amount reclassified from accumulated other comprehensive losses to interest expense	$ 63
Derivative Instrument, Gain Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense
Amount of (Gain) Loss Reclassified from Accumulated OCI into Earnings	$ (33,224)	$ 68,880	$ 3,702
Remaining unrecognized gains (losses) associated with derivative instruments included in AOCI	$ (9,701)	(6,338)
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	$ (3,090)	7,206	592
2020 Fixed-Rate Cross-Currency Swaps [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	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				$ 45,000
Fixed-Rate Cross Currency Interest Rate Contract [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Amount of (Gain) Loss Reclassified from Accumulated OCI into Earnings	$ (32,285)	$ 66,036	$ 3,725
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