Accumulated Other Comprehensive Loss (Income) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax [Roll Forward]
Beginning balance		$ (78,941)			$ (78,941)
Change during the period	$ 484	6	$ (298)	$ (124)	490
Ending balance	(78,451)				(78,451)
Accumulated Other Comprehensive (Income) Loss, Change in Fair Value of Hedging Instrument [Roll Forward]
Beginning balance		47			47
Change during the period					411
Ending balance	458				458
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, After Tax [Roll Forward]
Beginning balance		20,314			20,314
Change during the period					1,932
Ending balance	22,246				22,246
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (58,580)			(58,580)
Change during the period	241		$ (1,600)		2,833
Ending balance	$ 55,747				$ 55,747