Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets - Additional Information (Detail)

v3.8.0.1
Intangible Assets - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]        
Amortization of intangible assets $ 1.4 $ 1.4 $ 4.2 $ 3.8