Income Tax Expense - Total Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Expense
Income tax expense from continuing operations	$ 17,175	$ 13,510	$ 20,388
Income tax expense from discontinued operations	0	23,501	789
Total income tax expense (benefit)	$ 17,175	$ 37,011	$ 21,177