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Investments and Restricted Cash and Investments Investments and Restricted Cash and Investments (Details) - MidAmerican Energy Company [Member] - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Decommissioning Fund Investments, Fair Value $ 429 $ 424
Life Insurance, Corporate or Bank Owned, Amount 175 175
Available-for-sale Securities, Equity Securities 26 26
Other Investments 4 0
Investments, including equity method and restricted cash and investments, noncurrent $ 634 $ 625
Domestic Equity Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Nuclear Decommissioning Trust Fund Ownership Percentage 56.00% 56.00%
US Government Corporations and Agencies Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Nuclear Decommissioning Trust Fund Ownership Percentage 31.00% 32.00%
Domestic Corporate Debt Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Nuclear Decommissioning Trust Fund Ownership Percentage 9.00% 9.00%
Other Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Nuclear Decommissioning Trust Fund Ownership Percentage 4.00% 3.00%
Auction Rate Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Available-for-sale Debt Securities, Amortized Cost Basis $ 35 $ 35
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities 3  
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax $ 3 $ 3
Minimum [Member] | Auction Rate Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Available-for-Sale Securities, Remaining Maturity 2 years  
Maximum [Member] | Auction Rate Securities [Member]    
Investments, Including Equity Method And Restricted Cash And Investments [Line Items]    
Available-for-Sale Securities, Remaining Maturity 20 years