Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 28,813	$ 29,527
Noncurrent contract liabilities	396,175	386,324
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	5,262	4,771
Noncurrent contract liabilities	236,913	234,237
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	2,668	4,192
Noncurrent contract liabilities	37	290
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	13,654	14,169
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	7,229	6,395
Noncurrent contract liabilities	$ 159,225	$ 151,797