Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Current
Federal	$ 0	$ 0	$ (10,099)
State	14,193	8,412	11,075
Deferred
Federal	143,039	113,331	150,556
State (1)	(11,879)	17,160	15,330
TCJA Impact	0	0	(158,782)
Income tax expense (benefit)	145,353	138,903	8,080
Remeasurement due to state deferred tax rate change	$ 20,962	$ 0	$ 0

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