Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Assets:
Derivative financial instruments	$ 36,902	$ 12,335
Recurring
Assets:
Cash and cash equivalents	237,685	185,979
Other long-term investments	1,541	1,439
Derivative financial instruments	43,027	12,335
Total assets	282,253	199,753
Liabilities:
Derivative financial instruments	489	3,383
Total liabilities	489	3,383
Recurring | Level 1
Assets:
Cash and cash equivalents	237,685	185,979
Other long-term investments	1,541	1,439
Derivative financial instruments	0	0
Total assets	239,226	187,418
Liabilities:
Derivative financial instruments	0	0
Total liabilities	0	0
Recurring | Level 2
Assets:
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	43,027	12,335
Total assets	43,027	12,335
Liabilities:
Derivative financial instruments	489	3,383
Total liabilities	489	3,383
Recurring | Level 3
Assets:
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	0	0
Total assets	0	0
Liabilities:
Derivative financial instruments	0	0
Total liabilities	$ 0	$ 0