Contract Balance - Deferred Revenues (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Contract with Customer, Liability	$ 106,895	$ 108,978	$ 110,763	$ 122,141
Revenue recognized that was included in the deferred revenues balance at the beginning of the period	(70,160)	(75,600)
Increases due to billings, excluding amounts recognized as revenue during the period	66,292	78,945
Deferred revenue, reclassified as liabilities related to assets held for sale	0	$ (16,508)
Deferred revenue, current portion	102,500		105,400
Deferred revenue, noncurrent	$ 4,400		$ 5,400