Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	$ 38,062	$ 45,237	$ 44,189	$ 46,362	$ 48,595	$ 50,132
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(5,396)		(4,955)
Retirement plan liability adjustment, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(3,352)		(3,674)
Total accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	$ (8,748)	$ (9,002)	$ (8,629)	$ (8,965)	$ (8,078)	$ (9,250)