Revenue (Schedule of Uncollectible Amounts And Change in Expected Allowance for Credit Losses for Trade Accounts Receivable and Unbilled Receivables) (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
		Mar. 31, 2021	Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
Balance, beginning		$ 7,499	$ 8,359
Additions charged to costs and expenses, or sales allowance		1,040	1,128
Deductions		(837)	(2,008)
Other (deductions) additions	[1]	(180)	43
Balance, ending		$ 7,522	$ 7,522

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