Segment Information and Geographic Information - Additional Information (Detail) - Segment
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Segment Reporting Information [Line Items]      
Number of operating segment 1    
United States [Member]      
Segment Reporting Information [Line Items]      
Percentage of net revenues 96.00% 96.00% 96.00%