Revenue from Contracts with Customers Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2019	Mar. 31, 2019	Mar. 31, 2019	Sep. 30, 2018
Contract with Customer, Asset and Liability [Abstract]
Receivables, which are included in “Accounts receivable, net”			$ 275,222	$ 270,181
Deferred revenue	$ 110,730	$ 108,118	$ 110,730	$ 108,118
Contract With Customer, Liability [Roll Forward]
Deferred revenues, beginning balance		108,118
Revenue recognized that was included in the deferred revenues balance at the beginning of the period	(74,858)
Increases due to billings, excluding amounts recognized as revenue during the period	77,470
Deferred revenues, ending balance	$ 110,730	$ 110,730
Minimum
Disaggregation of Revenue [Line Items]
Payment term		30 days
Maximum
Disaggregation of Revenue [Line Items]
Payment term		60 days