Commitments and Contingencies - Additional Information (Detail) € in Thousands, £ in Thousands, $ in Thousands	Jul. 20, 2016 patent	Sep. 08, 2014 complaint	May 16, 2014 patent	Dec. 31, 2017 EUR (€) ft²	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2017 GBP (£) ft²	Nov. 30, 2017 EUR (€)	Nov. 30, 2017 USD ($)
Loss Contingencies [Line Items]
Annual base rent					$ 1,000
Tenant improvement allowances					1,000
Unamortized lease incentives					900
IDchecker
Loss Contingencies [Line Items]
Annual base rent				€ 197	236		€ 48	$ 57
Other current liabilities
Loss Contingencies [Line Items]
Unamortized lease incentives					100
Other non-current liabilities
Loss Contingencies [Line Items]
Unamortized lease incentives					$ 800
Building
Loss Contingencies [Line Items]
Amended office space subject to the lease (in square feet) | ft²				28,791	28,791	28,791
Sales Office
Loss Contingencies [Line Items]
Annual base rent					$ 104	£ 77
RMII Patent Infringement Case
Loss Contingencies [Line Items]
Number of patents allegedly infringed | patent			4
Number of additional claims filed | complaint		3
Number of patents not found to be infringed upon | patent	4