Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit), Including Discontinued Operations	$ 4,200		$ 3,900
(Benefit) expense from income taxes	4,170	$ (38,158)	3,959	$ (42,080)
Tax credit			800	5,400
Inventory impairments and abandonments	$ 0	$ 147,611	$ 0	$ 148,618
Deferred tax assets, tax credit carryforwards					$ 4,600