Income Taxes Summary of Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Domestic	$ 19,927	$ 81,276	$ (9,140)
Foreign	41,815	40,490	10,256
Income before income taxes	$ 61,742	$ 121,766	$ 1,116