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Segment, Product and Geographic Information (Details 5) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Jan. 01, 2017
Disclosure of operating segments [line items]      
Accounts receivable $ 87,963 $ 90,108 $ 92,530
Customer A And Its Affiliates [Member]      
Disclosure of operating segments [line items]      
Accounts receivable 63,501 61,100 55,681
Customer B And Its Affiliates [Member]      
Disclosure of operating segments [line items]      
Accounts receivable $ 24,462 $ 29,008 $ 36,849