Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) Client	Sep. 30, 2018 USD ($) Client	Jun. 30, 2019 USD ($) Client	Jul. 01, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash as collateral for letters of credit | $		$ 900
Right of use assets | $	$ 12,114		$ 0	$ 13,100
Lease liability | $	$ 15,470			$ 16,700
Customer Concentration Risk [Member] | Net revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of clients accounted for more than 10% of net revenue	1	1
Concentration risk percentage accounted by major clients	18.00%	25.00%
Number of other clients accounted for more than 10% of net revenue	0	0
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of other clients accounted for more than 10% of net accounts receivable	0		0
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Client Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage accounted by major clients	10.00%		11.00%
Number of clients accounted for 10% or more than 10% of net accounts receivable	1		1