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Revenue and Vendor Concentrations - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Revenue, Major Customer [Line Items]
Revenue	$ 16,109	$ 11,798	$ 42,522	$ 32,486
Accounts receivable, net	12,124		12,124		$ 7,099
Customer Concentration Risk \| Sales Revenue Net
Revenue, Major Customer [Line Items]
Revenue	7,900	5,000	$ 10,100	11,800
Total revenue, percentage			24.00%
Customer Concentration Risk \| Accounts Receivable
Revenue, Major Customer [Line Items]
Accounts receivable, net	$ 4,500	$ 3,600	$ 4,500	$ 3,600
Customer Concentration Risk \| Customer One \| Sales Revenue Net
Revenue, Major Customer [Line Items]
Total revenue, percentage	26.00%	28.00%		25.00%
Customer Concentration Risk \| Customer Two \| Sales Revenue Net
Revenue, Major Customer [Line Items]
Total revenue, percentage	13.00%	15.00%		11.00%
Customer Concentration Risk \| Customer Three \| Sales Revenue Net
Revenue, Major Customer [Line Items]
Total revenue, percentage	10.00%
Geographic Concentration Risk \| Sales Revenue Net
Revenue, Major Customer [Line Items]
Total revenue, percentage	24.00%	14.00%	25.00%	14.00%