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Commitments and Contingencies - Additional Information (Details) - 9 months ended Sep. 30, 2016
$ in Millions
USD ($)
MBbls
MMcf
Commitments And Contingencies [Line Items]      
Total rental commitments under leases $ 20.7    
Future obligations under purchase agreements $ 38.4    
Williston Basin Project [Member] | Long Term Commitments [Member]      
Commitments And Contingencies [Line Items]      
Maximum commitment term (less than) 10 years    
Future obligations under supply agreements $ 443.1    
Williston Basin Project [Member] | Crude oil [Member] | Long Term Commitments [Member]      
Commitments And Contingencies [Line Items]      
Minimum quantity of delivery (in MBbl of crude oil, MBbl of natural gas liquids, and MMcf of natural gas) | MBbls   43,800  
Williston Basin Project [Member] | Natural Gas [Member] | Long Term Commitments [Member]      
Commitments And Contingencies [Line Items]      
Minimum quantity of delivery (in MBbl of crude oil, MBbl of natural gas liquids, and MMcf of natural gas)   23,000 216,700