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Segments and Related Information - Narrative (Details)
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
supplier
Segment Reporting Information [Line Items]    
Number of customers representing 10% or greater of consolidated sales no 0
number of major suppliers 2 2
Disclosure on Geographic Areas, Description of Revenue from External Customers ten percent .1
Supplier Concentration Risk [Member]    
Segment Reporting Information [Line Items]    
Percentage of crude oil supply from 2 suppliers 52.10% 58.30%