Commitments and Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2016 USD ($) ft²	Dec. 31, 2016 EUR (€) ft²	Dec. 31, 2016 GBP (£) ft²
Loss Contingencies [Line Items]
Commencement date of term of lease	Oct. 01, 2016
Expiration date of term of lease	Apr. 30, 2020
Annual base rent	$ 0.6
Tenant improvement allowances	0.3
Unamortized lease incentives	$ 0.3
IDchecker [Member]
Loss Contingencies [Line Items]
Expiration date of term of lease	May 31, 2020
Annual base rent | €		€ 48,000
Building [Member]
Loss Contingencies [Line Items]
Amended office space subject to the lease | ft²	28,354	28,354	28,354
Sales office [Member]
Loss Contingencies [Line Items]
Expiration date of term of lease	May 31, 2017
Annual base rent | £			£ 65,000
Other current liabilities [Member]
Loss Contingencies [Line Items]
Unamortized lease incentives	$ 0.1
Other non-current liabilities [Member]
Loss Contingencies [Line Items]
Unamortized lease incentives	$ 0.2