Debt (Schedule of Line of Credit Facilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity	$ 60,000	$ 60,000
Debt instrument, unused borrowing capacity, amount	50,396	49,888
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity	350,000	350,000
Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	9,604	10,112
Debt instrument, unused borrowing capacity, amount	119,396	302,888
2021 Revolving Credit Facility, due April 2026
Line of Credit Facility [Line Items]
line of Credit Facility, Amount Drawn	$ 221,000	$ 37,000