XML 73 R35.htm IDEA: XBRL DOCUMENT v3.20.1
Summary of Significant Accounting Policies - Concentration (Details) - customer
3 Months Ended 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Dec. 31, 2019
Sales | Customer      
Risk and Uncertainties      
Number of customers exceeding 10% of benchmark 0 0  
Concentration risk (as a percent) 10.00%    
Accounts receivable | Credit      
Risk and Uncertainties      
Number of customers exceeding 10% of benchmark 0   0
Concentration risk (as a percent) 10.00%