Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Estimated Annual Effective Tax Rate Used to Calculate Income Tax Expense (Benefit)	4.90%	25.80%
Federal statutory income tax rate, percent	21.00%
Effective income tax rate reconciliation, percent	4.60%
Income tax (expense) benefit	$ (2,603)	$ 4,514
Income (loss) before income taxes	56,109	$ (20,802)
Unrecognized Tax Benefits	$ 1,289