Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2020 USD ($) Swap	Jun. 30, 2021 USD ($) loan	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) loan	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	May 31, 2018 USD ($) loan	Sep. 23, 2016 EUR (€)
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	$ 30,000
Proceed from net interest accrued on swap contracts settlement		$ 575,774		$ 575,774		$ 546,346
Remaining unrecognized gains (losses) associated with derivative instruments included in AOCI		(27,014)		$ (27,014)		$ (21,132)
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		$ 750	$ 792	$ 648	$ (1,187)
Floating-Rate Cross Currency Interest Rate Contract [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount							$ 167,420
2020 Fixed-Rate Cross-Currency Swaps [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	$ 400,000
2020 Fixed-Rate Cross-Currency Swaps [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount							400,000
Derivative, number of instruments | Swap	5
2020 Floating-Rate Cross-Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	$ 45,000
Floating Rate Cross Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	108,823
Fixed Rate Cross Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount	400,000
Floating-Rate Cross-Currency Swap and Fixed-Rate Cross-Currency Swap [Member]
Derivative Instruments Gain Loss [Line Items]
Proceeds from swap contracts settlement	59,571
Derivative asset, fair value	58,191
Proceed from net interest accrued on swap contracts settlement	4,380
Swap termination fee	$ 3,000
Fixed-Rate Cross Currency Interest Rate Contract [Member] | Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative, notional amount							$ 400,000
Derivative, number of instruments | loan		5		5			5