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Segment Information and Foreign Operations - Concentration of Credit Risk (Details) - Customer concentration
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
customer
Sep. 30, 2020
customer
Sep. 30, 2021
customer
Sep. 30, 2020
customer
Dec. 31, 2020
customer
Revenues          
Revenue, Major Customer [Line Items]          
Number of customers representing significant share 0 0 0 2  
Accounts Receivable          
Revenue, Major Customer [Line Items]          
Number of customers representing significant share     1   2
Landmark | Revenues          
Revenue, Major Customer [Line Items]          
Percentage share generated by major customers       11.00%  
Osram | Revenues          
Revenue, Major Customer [Line Items]          
Percentage share generated by major customers       10.00%  
Major Customer One | Accounts Receivable          
Revenue, Major Customer [Line Items]          
Percentage share generated by major customers     11.00%   11.00%
Major Customer Two | Accounts Receivable          
Revenue, Major Customer [Line Items]          
Percentage share generated by major customers         10.00%
Top Five Major Customers | Revenues          
Revenue, Major Customer [Line Items]          
Number of customers representing significant share 5 5 5 5  
Percentage share generated by major customers 25.00% 29.00% 26.00% 33.00%