Property, Plant, and Equipment (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Net (gain) loss on sales of assets	[1]	$ (13,547)	$ 79
Impairment of assets held for sale		37,902
Duarte Facility [Member]
Property, Plant and Equipment [Line Items]
Net (gain) loss on sales of assets		(13,522)
Renewable Power Systems [Member]
Property, Plant and Equipment [Line Items]
Impairment of assets held for sale		37,902
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Duarte Facility [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment remaining		2,520
Plant, Property and Equipment [Member] | Renewable Power Systems [Member]
Property, Plant and Equipment [Line Items]
Impairment of assets held for sale		$ 13,158

[1] Included in net (gain) loss on sale of assets for the first quarter of fiscal year 2020 was the pre-tax gain on sale of Duarte real property in the amount of $13,522.