Financial Instruments and Fair Value Measurements (Financial Assets that are Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Financial assets:
Total financial assets	$ 230,407	$ 178,651
Financial liabilities:
Total financial liabilities	83,137	51,387
Cross Currency Interest Rate Swaps [Member]
Financial liabilities:
Cross-currency interest rate swaps	83,137	51,387
Level 1 [Member]
Financial assets:
Total financial assets	230,407	178,651
Level 2 [Member]
Financial liabilities:
Total financial liabilities	83,137	51,387
Level 2 [Member] | Cross Currency Interest Rate Swaps [Member]
Financial liabilities:
Cross-currency interest rate swaps	83,137	51,387
Cash [Member]
Financial assets:
Cash	188,104	112,817
Cash [Member] | Level 1 [Member]
Financial assets:
Cash	188,104	112,817
Investments in Term Deposits with Foreign Banks [Member]
Financial assets:
Investments	13,777	40,453
Investments in Term Deposits with Foreign Banks [Member] | Level 1 [Member]
Financial assets:
Investments	13,777	40,453
Equity Securities [Member]
Financial assets:
Equity securities	28,526	25,381
Equity Securities [Member] | Level 1 [Member]
Financial assets:
Equity securities	$ 28,526	$ 25,381