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Income Taxes - MidAmerican Funding (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]      
Federal statutory income tax rate 21.00% 35.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (45.00%) (16.00%)  
State income tax, net of federal income tax benefit 30.00% 5.00%  
Effects of ratemaking (8.00%) (1.00%)  
Other (1.00%) (0.00%)  
Effective income tax rate 78.00% (9.00%)  
Production Tax Credit Carryforwards [Abstract]      
Years eligible for federal renewable energy production tax credit 10 years    
Related Party Income Tax Receivable (Payable) [Abstract]      
Related party transaction, cash received for income taxes, net $ 0 $ 0  
MidAmerican Funding, LLC and Subsidiaries [Domain]      
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]      
Federal statutory income tax rate 21.00% 35.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (151.00%) (87.00%)  
State income tax, net of federal income tax benefit (10.00%) 2.00%  
Effects of ratemaking (20.00%) (13.00%)  
Other 2.00% (2.00%)  
Effective income tax rate (158.00%) (65.00%)  
Production Tax Credit Carryforwards [Abstract]      
Years eligible for federal renewable energy production tax credit 10 years    
MidAmerican Funding, LLC and Subsidiaries [Domain] | Berkshire Hathaway Energy [Member]      
Related Party Income Tax Receivable (Payable) [Abstract]      
Related party transaction, cash received for income taxes, net $ 14 $ 0  
Tax Cuts and Jobs Act of 2017 [Member]      
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]      
Federal statutory income tax rate 21.00%    
Tax Cuts and Jobs Act of 2017 [Member] | MidAmerican Funding, LLC and Subsidiaries [Domain]      
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]      
Federal statutory income tax rate 21.00%