XML 97 R84.htm IDEA: XBRL DOCUMENT v3.20.4
Industry, Geographic, and Revenue Disaggregation - Narrative (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2020
USD ($)
segment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
Segment Reporting [Abstract]      
Number of operating segments | segment 1    
Concentration Risk [Line Items]      
Trade accounts receivable $ 1,550 $ 3,222  
Lease income $ 3,600 $ 1,300  
Total Revenue | One Customer      
Concentration Risk [Line Items]      
Risk concentration 8.00% 28.00% 27.00%
Accounts Receivable | Geographic Concentration | Outside the U.S.      
Concentration Risk [Line Items]      
Trade accounts receivable $ 300 $ 2,100