Commitments and Contingencies Commitments and Contingencies - MEC - Transmission Rates (Details) - MidAmerican Energy Company [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 9
Electric Transmission [Member]
Loss Contingencies [Line Items]
Public Utilities, Approved Return on Equity Adder, Percentage	0.50%
Electric Transmission [Member] | Prior to September 2016 [Member]
Loss Contingencies [Line Items]
Public Utilities, Approved Return on Equity, Percentage	12.38%
Electric Transmission [Member] | 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%
Electric Transmission [Member] | February 2015 through May 2016 [Member]
Loss Contingencies [Line Items]
Public Utilities, Intervenor Proposed Return On Equity, Percentage	8.67%