Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Income Taxes [Line Items]
Gross unrecognized tax benefits	$ 13,314	$ 9,851
Unrecognized tax benefits that, if recognized, would affect the effective tax rate	7,349
Possible decrease in unrecognized tax benefits liability	$ 1,884
Domestic Tax Authority [Member]
Income Taxes [Line Items]
Year remaining open to tax examination	2018
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Year remaining open to tax examination	2016
Foreign Jurisdiction [Member]
Income Taxes [Line Items]
Year remaining open to tax examination	2016