XML 41 R41.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Significant Accounting Policies - Schedule of Concentration Risk (Details) - Sales Revenue, Product Line - Customer Concentration Risk
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Occidental Petroleum Corp.      
Concentration Risk [Line Items]      
Concentration risk (as a percentage) 16.00% 15.00% 0.00%
Continental Resources, Inc.      
Concentration Risk [Line Items]      
Concentration risk (as a percentage) 12.00% 10.00% 10.00%
XTO Energy, Inc.      
Concentration Risk [Line Items]      
Concentration risk (as a percentage) 10.00% 0.00% 0.00%
Noble Energy, Inc.      
Concentration Risk [Line Items]      
Concentration risk (as a percentage) 5.00% 9.00% 13.00%