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Intangible Assets - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Intangible Assets Net Excluding Goodwill [Abstract]        
Amortization expense $ 1.3 $ 0.9 $ 4.0 $ 2.4