Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 33,748	$ 30,663
Noncurrent contract liabilities	414,657	396,345
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,147	5,754
Noncurrent contract liabilities	233,997	234,516
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,868	4,120
Noncurrent contract liabilities	2,196	38
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	14,543	12,442
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,190	8,347
Noncurrent contract liabilities	$ 178,464	$ 161,791