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Segments and Related Information - Narrative (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2020
supplier
Jun. 30, 2019
supplier
Jun. 30, 2020
Jun. 30, 2019
supplier
Segment Reporting Information [Line Items]        
Number of customers representing 10% or greater of consolidated sales 0 0 no 0
number of major suppliers 2 2 2 2
Disclosure on Geographic Areas, Description of Revenue from External Customers .1 .1 ten percent .1
Supplier Concentration Risk [Member]        
Segment Reporting Information [Line Items]        
Percentage of crude oil supply from 2 suppliers     57.20% 67.70%