Risk Management and Hedging Activities (MEC) Derivative Contract Volumes (Details) - MidAmerican Energy Company [Member] - Commodity Contract [Member] MWh in Millions, Dth in Millions	Jun. 30, 2015 MWh Dth	Dec. 31, 2014 MWh Dth
Electricity purchases (in megawatt hours) [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount	16	14
Natural gas purchases (in decatherms) [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount | Dth	17	19