Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense (benefit), including discontinued operations	$ (38,200)	$ 1,000	$ (42,100)	$ 109,000
Inventory impairments and abandonments	147,611	$ 0	148,618	0
Tax credit			5,400	$ 2,300
Deferred tax assets, tax credit carryforwards	$ 9,600		$ 9,600