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North Dakota Public Service Commission (NDPSC) (Details 2) - NDPSC - USD ($)
$ in Millions
Sep. 26, 2018
Aug. 10, 2018
Mar. 09, 2018
Mar. 01, 2018
Feb. 14, 2018
Sep. 06, 2017
Jul. 21, 2017
Natural gas rate proceeding              
Public Utilities, General Disclosures [Line Items]              
Public utilities, requested rate increase (decrease), amount             $ 5.9
Public utilities, requested rate increase (decrease), percentage             5.40%
Public utilities, interim rate increase (decrease), amount           $ 4.6  
Public utilities, interim rate increase (decrease), percentage           4.20%  
Natural gas rate proceeding | Tax Cuts and Jobs Act              
Public Utilities, General Disclosures [Line Items]              
Public utilities interm rate increase (decrese) revised         $ 2.7    
Public utilities, requested rate increase (decrease), amended, amount       $ 3.6      
Public Utilities, Approved Rate Increase (Decrease), Amount $ 2.5            
Public utilities, approved rate increase (decrease), percentage 2.30%            
Electric rate proceeding | Tax Cuts and Jobs Act              
Public Utilities, General Disclosures [Line Items]              
Public utilities, requested rate increase (decrease), amount     $ (7.2)        
Public utilities, requested rate increase (decrease), percentage     (3.90%)        
Public utilities, requested rate increase (decrease), amended, amount   $ (8.4)