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Segment Information and Geographic Data - Additional Information (Detail) - Segment
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Segment Reporting Information [Line Items]      
Number of operating segment 1    
Revenue [Member] | Outside Of United States [Member] | Geographic Concentration Risk [Member]      
Segment Reporting Information [Line Items]      
Concentration risk, percentage 40.00% 37.00% 33.00%