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Income Taxes - MEC - Reconciliation of Effective Income Tax Rate (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Schedule of Effective Income Tax Rate Reconciliation [Line Items]        
Federal statutory income tax rate 21.00% 21.00% 21.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (16.00%) (32.00%) (30.00%)  
State income tax, net of federal income tax benefit (3.00%) 5.00% 6.00%  
Effective Income Tax Rate Reconciliation Regulatory Differences (3.00%) (6.00%) (8.00%)  
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent 0.00% 0.00% (4.00%)  
Other, net (1.00%) (1.00%) (1.00%)  
Effective income tax rate 4.00% (25.00%) (30.00%)  
Years Eligible For Renewable Energy Production Tax Credit 10 years      
MidAmerican Energy Company [Member]        
Schedule of Effective Income Tax Rate Reconciliation [Line Items]        
Federal statutory income tax rate 21.00% 21.00% 21.00% 35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent (199.00%) (90.00%) (73.00%)  
State income tax, net of federal income tax benefit (27.00%) (11.00%) (4.00%)  
Effective Income Tax Rate Reconciliation Regulatory Differences (17.00%) (8.00%) (5.00%)  
Other, net (1.00%) 0.00% 1.00%  
Effective income tax rate (223.00%) (88.00%) (60.00%)  
Years Eligible For Renewable Energy Production Tax Credit 10 years      
Tax Cuts and Jobs Act of 2017 [Member]        
Schedule of Effective Income Tax Rate Reconciliation [Line Items]        
Federal statutory income tax rate       21.00%
Tax Cuts and Jobs Act of 2017 [Member] | MidAmerican Energy Company [Member]        
Schedule of Effective Income Tax Rate Reconciliation [Line Items]        
Federal statutory income tax rate     21.00%