Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 31,567	$ 30,663
Noncurrent contract liabilities	412,608	396,345
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	6,049	5,754
Noncurrent contract liabilities	235,686	234,516
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	4,771	4,120
Noncurrent contract liabilities	3,277	38
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	12,841	12,442
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	7,906	8,347
Noncurrent contract liabilities	$ 173,645	$ 161,791