Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2018	Dec. 31, 2017
Income Taxes [Line Items]
U.S. corporate income tax rate		21.00%	35.00%
Blended corporate tax rate		24.50%
Decrease in tax provision due to revaluation of net deferred tax liability		$ (43.4)
State
Income Taxes [Line Items]
Net operating losses	$ 94.7
Net operating losses, expiration start year	2020
Net operating losses, expiration end year	2040