Risk Management and Hedging Activities - MEC - Derivative Contract Volumes (Details) - Commodity Contract [Member] MWh in Millions, Dth in Millions	Dec. 31, 2015 Dth MWh	Dec. 31, 2014 Dth MWh
Electricity purchases (sales), net, in megawatt hours [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount | MWh	10	6
Electricity purchases (sales), net, in megawatt hours [Member] | MidAmerican Energy Company [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount | MWh	15	14
Natural gas purchases, in decatherms [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount | Dth	317	308
Natural gas purchases, in decatherms [Member] | MidAmerican Energy Company [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, Nonmonetary Notional Amount | Dth	17	19