Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 48,821	$ 33,748
Noncurrent contract liabilities	426,810	414,657
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,364	6,147
Noncurrent contract liabilities	235,837	233,997
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	17,414	6,868
Noncurrent contract liabilities	4,333	2,196
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	17,941	14,543
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	7,102	6,190
Noncurrent contract liabilities	$ 186,640	$ 178,464