Revenue from Contracts with Customers - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Sep. 30, 2019
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts receivable, net	$ 183,167	$ 183,167	$ 165,602
Contract with Customer, Asset, after Allowance for Credit Loss, Current [Abstract]
Contract assets	$ 15,500	$ 15,500	14,000
Capitalized Contract Cost [Abstract]
Sales commission amortization period	60 months	60 months
Deferred commissions	$ 500	$ 500	800
Deferred commission amortization expense	100	400
Contract with Customer, Liability [Abstract]
Current contract liabilities	31,162	31,162	29,435
Contract liabilities	31,200	$ 31,200	$ 29,400
Revenue recognized	$ 19,200