Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 37,122	$ 33,748
Noncurrent contract liabilities	419,939	414,657
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,255	6,147
Noncurrent contract liabilities	232,553	233,997
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	9,638	6,868
Noncurrent contract liabilities	4,196	2,196
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	14,357	14,543
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,872	6,190
Noncurrent contract liabilities	$ 183,190	$ 178,464