Business Information - Long-lived Assets by Geographic Areas (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 63,095	$ 66,741
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	54,109	56,134
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 8,986	$ 10,607