Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Accrued Liabilities, Current [Abstract]
Salaries and other member benefits	$ 89,797	$ 146,713
Product warranties and related liabilities	21,802	18,162	$ 49,526	$ 40,042
Interest payable	4,105	13,611
Accrued retirement benefits	2,869	2,822
Net current contract liabilities	37,122	33,748
Taxes, other than income	22,842	13,436
Other	33,120	34,124
Accrued liabilities	$ 211,657	$ 262,616