Commitments and Contingencies Commitments and Contingencies - MEC - Transmission Rates (Details) - MidAmerican Energy Company [Member] - Electric Transmission [Member] $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Loss Contingencies [Line Items]
Public Utilities, Approved Return on Equity Adder, Percentage	0.50%
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
Accrued liability for estimated transmission billings refunds	$ 10
Prior to September 2016 [Member]
Loss Contingencies [Line Items]
Public Utilities, Approved Return on Equity, Percentage	12.38%
November 2013 to February 2015 [Member]
Loss Contingencies [Line Items]
Public Utilities, Approved Return on Equity, Percentage	10.32%
Public Utilities, Intervenor Proposed Return On Equity, Percentage	9.15%
February 2015 through May 2016 [Member]
Loss Contingencies [Line Items]
Public Utilities, Intervenor Proposed Return On Equity, Percentage	8.67%