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Regulatory Matters - MEC - Regulatory Liabilities (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Regulatory Liabilities [Line Items]      
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 21.00% 35.00%
Regulatory liabilities $ 7,100 $ 7,346  
Cost of removal      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years [1] 26.8240506329114    
Deferred Income Tax Charge [Member]      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years [2] Various    
Asset retirement obligations      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years 33    
Tax Cuts and Jobs Act of 2017 [Member]      
Regulatory Liabilities [Line Items]      
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 21.00%  
MidAmerican Energy Company [Member]      
Regulatory Liabilities [Line Items]      
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 21.00% 35.00%
Regulatory liabilities $ 1,406 $ 1,620  
MidAmerican Energy Company [Member] | Cost of removal      
Regulatory Liabilities [Line Items]      
Regulatory Liability, Amortization Period [3] 29 years    
Regulatory liabilities [3] $ 572 708  
MidAmerican Energy Company [Member] | Deferred Income Tax Charge [Member]      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years [4] Various    
Regulatory liabilities [4] $ 478 626  
MidAmerican Energy Company [Member] | Asset retirement obligations      
Regulatory Liabilities [Line Items]      
Regulatory Liability, Amortization Period [4] 33 years    
Regulatory liabilities [4] $ 241 160  
MidAmerican Energy Company [Member] | Pension and other postretirement costs [Member]      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years P10Y    
Regulatory liabilities [5] $ 32 0  
MidAmerican Energy Company [Member] | Transmission MVP CWIP Return [Member]      
Regulatory Liabilities [Line Items]      
Regulatory Liability, Amortization Period [6] 53 years    
Regulatory liabilities [6] $ 35 36  
MidAmerican Energy Company [Member] | Regulatory revenue sharing arrangement [Member]      
Regulatory Liabilities [Line Items]      
Regulatory Liability, Amortization Period [7] 1 year    
Regulatory liabilities [7] $ 22 70  
MidAmerican Energy Company [Member] | Other      
Regulatory Liabilities [Line Items]      
Regulatory liability amortization period years Various    
Regulatory liabilities $ 26 $ 20  
MidAmerican Energy Company [Member] | Tax Cuts and Jobs Act of 2017 [Member]      
Regulatory Liabilities [Line Items]      
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00%    
[1] Amounts represent estimated costs, as accrued through depreciation rates and exclusive of ARO liabilities, of removing regulated property, plant and equipment in accordance with accepted regulatory practices. Amounts are deducted from rate base or otherwise accrue a carrying cost.
[2] (1)Amounts primarily represent income tax liabilities related to the federal tax rate change from 35% to 21% that are probable to be passed on to customers, offset by income tax benefits related to certain property-related basis differences and other various differences that were previously passed on to customers and will be included in regulated rates when the temporary differences reverse. See Note 12 for further discussion of 2017 Tax Reform impacts.
[3] Amounts represent estimated costs, as accrued through depreciation rates and exclusive of ARO liabilities, of removing utility plant in accordance with accepted regulatory practices. Amounts are deducted from rate base or otherwise accrue a carrying cost.
[4] Amount represents the excess of nuclear decommission trust assets over the related asset retirement obligation. Refer to Note 11 for a discussion of asset retirement obligations.
[5] Represents current-year accruals under a regulatory arrangement in Iowa in which equity returns exceeding specified thresholds reduce utility plant upon final determination.
[6] Represents amounts not yet recognized as a component of net periodic benefit cost that are to be returned to customers in future periods when recognized.
[7] Represents AFUDC accrued on transmission MVPs that is deducted from rate base as a result of the inclusion of related construction work-in-progress in rate base.