Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022
Accrued Liabilities, Current [Abstract]
Salaries and other member benefits	$ 98,019		$ 146,713
Product warranties and related liabilities	19,800	$ 21,802	18,162	$ 46,492	$ 49,526	$ 40,042
Interest payable	12,199		13,611
Accrued retirement benefits	2,844		2,822
Net current contract liabilities	48,821		33,748
Taxes, other than income	18,981		13,436
Other	36,280		34,124
Accrued liabilities	$ 236,944		$ 262,616