Income Tax Expense - Tax Effects Of Temporary Differences That Give Rise To Significant Portions Of The Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Deferred tax assets:
Inventories	$ 5,089	$ 5,834
Pension and other postretirement benefits	5,533	3,969
Net operating and capital loss carryforwards - domestic	617	639
Net operating loss carryforward - foreign	3,766	4,603
Foreign tax credit carryforward	0	2,377
Other compensation-related costs and other cost accruals	7,952	7,048
State credit carryforward	1,914	2,103
Total deferred tax assets	24,871	26,573
Deferred tax liabilities:
Timing differences related to revenue recognition	(1,508)	0
Goodwill	(2,673)	(969)
Acquisition assets	(60,224)	(62,841)
Depreciation, software amortization	(20,161)	(19,584)
Net deferred tax liabilities before valuation allowance	59,695	56,821
Less valuation allowance	(4,520)	(7,144)
Net deferred tax liabilities	$ (64,215)	$ (63,965)