Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Current federal (a)	$ (4,935)	$ 57	$ 0
Current state	693	512	859
Deferred federal	(31,291)	102,082	1,625
Deferred state	(1,684)	(8,167)	212
Total (benefit) / expense	$ (37,217)	$ 94,484	$ 2,696