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Operating Segment and Related Information - Schedules of Concentration of Risk (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Customer A | Telecommunications | Customer risk | Sales Revenue        
Concentration Risk [Line Items]        
Concentration risk 10.40% 11.90% 10.50% 11.30%