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Geographic Information - Narrative (Details) - segment
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Segment Reporting [Abstract]      
Number of operating segments 1    
United States | Revenue | Geographic concentration risk      
Concentration Risk [Line Items]      
Concentration risk, percentage 63.00% 67.00% 69.00%