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Income Taxes - MEC (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]          
Federal statutory income tax rate 21.00% 35.00% 21.00% 35.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (19.00%) (19.00%) (29.00%) (18.00%)  
State income tax, net of federal income tax benefit 1.00% (0.00%) (6.00%) (1.00%)  
Effects of ratemaking (2.00%) (0.00%) (3.00%) (0.00%)  
Other, net 1.00% 1.00% 1.00% (0.00%)  
Effective income tax rate (2.00%) (15.00%) 19.00% (13.00%)  
Production Tax Credit Carryforwards [Abstract]          
Years eligible for federal renewable energy production tax credit     10 years    
MidAmerican Energy Company [Member]          
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]          
Federal statutory income tax rate 21.00% 35.00% 21.00% 35.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (95.00%) (74.00%) (97.00%) (74.00%)  
State income tax, net of federal income tax benefit (10.00%) (10.00%) (9.00%) (7.00%)  
Effects of ratemaking (4.00%) (2.00%) (7.00%) (4.00%)  
Other, net (0.00%) (1.00%) (1.00%) (0.00%)  
Effective income tax rate (88.00%) (52.00%) (93.00%) (50.00%)  
Production Tax Credit Carryforwards [Abstract]          
Years eligible for federal renewable energy production tax credit     10 years    
MidAmerican Energy Company [Member] | Berkshire Hathaway Energy [Member]          
Related Party Income Tax Receivable (Payable) [Abstract]          
Related party transaction, cash received for income taxes, net     $ 232 $ 381