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Financial Instruments - Additional Information (Detail) - USD ($)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Sep. 30, 2016
Dec. 31, 2015
Fair Value Of Financial Instruments [Line Items]        
Fair value of note payable $ 5,300 $ 5,300    
Cash and cash equivalents 24,567 45,824 $ 41,814 $ 34,194
Cash held outside United States, principally in Netherlands, United Kingdom, China, and Canada 17,000 25,600    
Credit Facility [Member]        
Fair Value Of Financial Instruments [Line Items]        
Fair value of debt issued $ 117,900 $ 125,100