Assets Held for Sale and Discontinued Operations - Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations, net of tax	$ (6,647)	$ 1,774	$ (9,267)	$ 6,525
Provision for allowance for doubtful accounts, net			1,141	48
Solar Segment | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations, net of tax	$ (6,647)	$ 1,774	(9,267)	6,525
Depreciation and amortization			287	324
Provision for allowance for doubtful accounts, net			981	37
Purchases of property, plant and equipment			$ 96	$ 220