Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Reconciliation of Unrecognized Tax Benefits
Unrecognized tax benefits – beginning of year	$ 1,829	$ 2,055
Additions for tax positions taken in prior years	6	604	$ 2,055
Settlements with tax authorities/statute lapses	(1,147)	(830)	0
Unrecognized tax benefits – end of year	$ 688	$ 1,829	$ 2,055