Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018
Accrued Liabilities [Abstract]
Salaries and other member benefits		$ 37,514		$ 115,649
Warranties		21,770	$ 18,927	27,309	$ 21,680	$ 20,156	$ 20,130
Interest payable		13,735		13,808
Accrued retirement benefits		3,596		3,587
Current portion of loss reserve on contractual lease commitments	[1]			1,245
Restructuring charges				507
Taxes, other than income		15,740		15,708
Net current contract liabilities (Note 3)		25,601		27,891
Liabilities held for sale (Note 10)		14,273
Other		22,330		22,423
Accrued liabilities		$ 154,559		$ 228,127

[1] See Note 17, Other liabilities, for more information on loss reserve on contractual lease commitments.