Other Finance Income (Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Pension interest cost	$ (674)	$ (725)
Expected return on pension plan assets	909	916
Foreign currency translation on senior bank debt	(2,897)
Foreign currency remeasurement on hedging instrument	1,931
Other finance income (costs)	$ (731)	$ 191