Contract Balances and Performance Obligation - Contract Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2019
Contract With Customer, Liability [Roll Forward]
Deferred revenues at September 30, 2019	$ 116,320
Revenue recognized that was included in the deferred revenues balance at the beginning of the period	(91,337)
Increases due to billings, excluding amounts recognized as revenue during the period	86,749
Deferred revenues at June 30, 2020	111,732
Deferred revenue and other liabilities, current portion	105,800	$ 111,000
Deferred revenue and other liabilities, noncurrent	$ 5,900	$ 5,300