Revenue (Schedule of Contract Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Contract With Customer Liability [Line Items]
Current contract liabilities	$ 30,065	$ 29,527
Noncurrent contract liabilities	389,437	386,324
Deferred Revenue From Material Rights From GE Joint Venture Formation [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	5,017	4,771
Noncurrent contract liabilities	233,055	234,237
Deferred Revenue From Advance Invoicing And/Or Prepayments From Customers [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	2,207	4,192
Noncurrent contract liabilities	62	290
Liability Related To Customer Supplied Inventory [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	15,771	14,169
Deferred Revenue From Material Rights Related To Engineering And Development Funding [Member]
Contract With Customer Liability [Line Items]
Current contract liabilities	7,070	6,395
Noncurrent contract liabilities	$ 156,320	$ 151,797