Revenue (Schedule of Uncollectible Amounts And Change in Expected Allowance for Credit Losses for Trade Accounts Receivable and Unbilled Receivables) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Balance, beginning		$ 8,359	$ 8,936	$ 3,938
Charged to costs and expenses, or sales allowance		2,382	4,735	5,927
Deductions		(7,255)	(5,342)	(1,180)
Other additions	[1]	178	30	251
Balance, ending		$ 3,664	$ 8,359	$ 8,936

[1] Includes effects of foreign exchange rate changes during the period.