Accrued Liabilities (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Jun. 30, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Loss reserve on contractual lease commitments	[1]		$ 1,754	$ 2,686
Restructuring charges				17,013
Payments for restructuring			12,445	491
Non-cash adjustments			(3,570)
Loss Reserve On Contractual Lease Commitments [Member]
Restructuring Cost and Reserve [Line Items]
Payments for restructuring			$ 932	1,339	$ 1,650
Non-cash adjustments		$ 2,322			$ (2,322)
Duarte Plant Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 17,013

[1] See Note 15, Accrued liabilities for more information on the loss reserve on contractual lease commitments.