Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Detail)

v3.8.0.1
Commitments and Contingencies - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Commitments and Contingencies Disclosure [Line Items]      
Rent expense related to operating leases $ 3.2 $ 2.3 $ 2.0
Maximum      
Commitments and Contingencies Disclosure [Line Items]      
Payment required under certain channel distribution agreement upon revenue target achieved $ 0.5