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Risk Management and Hedging Activities - MEC - Balance Sheet Location (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net $ (17) $ (77)    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 76 74    
Derivative Assets (Liabilities), at Fair Value, Net 59 (3)    
Other Current Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 40 48    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 0    
Derivative Assets (Liabilities), at Fair Value, Net 40 48    
Other Current Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (60) (60)    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 18 13    
Derivative Assets (Liabilities), at Fair Value, Net (42) (47)    
Not Designated as Hedging Instrument [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (24) (66)    
Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 39 47    
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (59) (45)    
Designated as Hedging Instrument [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 7 (11)    
Designated as Hedging Instrument [Member] | Other Current Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 1 1    
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (1) (15)    
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (32) (71)    
Net Regulatory Asset (Liability), Unrealized Loss (Gain) On Derivative Contracts 119 148 $ 250 $ 223
MidAmerican Energy Company [Member] | Commodity Contract [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (3) 4    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 1    
Derivative Assets (Liabilities), at Fair Value, Net (3) 5    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Other Current Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 5 6    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 0    
Derivative Assets (Liabilities), at Fair Value, Net 5 6    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net 0 2    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 0    
Derivative Assets (Liabilities), at Fair Value, Net 0 2    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (6) (3)    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 1    
Derivative Assets (Liabilities), at Fair Value, Net (6) (2)    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative, Fair Value, Net (2) (1)    
Cash Collateral, Net Receivable (Payable), Offset Against Derivative Positions 0 0    
Derivative Assets (Liabilities), at Fair Value, Net (2) (1)    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]        
Derivatives, Fair Value [Line Items]        
Derivative Asset, Fair Value, Gross Asset [1] 7 10    
Derivative Liability, Fair Value, Gross Liability [1] (10) (6)    
Derivative, Fair Value, Net [1] (3) 4    
Net Regulatory Asset (Liability), Unrealized Loss (Gain) On Derivative Contracts 3 (4) $ 20 $ 38
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative Asset, Fair Value, Gross Asset [1] 6 8    
Derivative Liability, Fair Value, Gross Liability [1] (1) (2)    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member]        
Derivatives, Fair Value [Line Items]        
Derivative Asset, Fair Value, Gross Asset [1] 0 2    
Derivative Liability, Fair Value, Gross Liability [1] 0 0    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative Asset, Fair Value, Gross Asset [1] 1 0    
Derivative Liability, Fair Value, Gross Liability [1] (7) (3)    
MidAmerican Energy Company [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]        
Derivatives, Fair Value [Line Items]        
Derivative Asset, Fair Value, Gross Asset [1] 0 0    
Derivative Liability, Fair Value, Gross Liability [1] $ (2) $ (1)    
[1] (1)MidAmerican Energy's commodity derivatives not designated as hedging contracts are generally included in regulated rates. Accordingly, as of December 31, 2017, a net regulatory asset of $3 million was recorded related to the net derivative a liability of $3 million, and as of December 31, 2016, a net regulatory liability of $(4) million was recorded related to the net derivative asset of $4 million