Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 29,548	$ 30,663
Noncurrent contract liabilities	409,262	396,345
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	5,950	5,754
Noncurrent contract liabilities	237,179	234,516
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	3,570	4,120
Noncurrent contract liabilities	63	38
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	14,779	12,442
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	5,249	8,347
Noncurrent contract liabilities	$ 172,020	$ 161,791