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Summary of Significant Accounting Policies (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Net sales | Customer concentration risk | Murphy USA        
Concentration Risk [Line Items]        
Major customer percentage of net sales 13.00% 15.00% 14.00% 15.00%