Business Information - Long-lived Assets by Geographic Areas (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 66,741	$ 46,641
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	56,134	35,079
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 10,607	$ 11,562