Risk Management and Hedging Activities - MEC - Derivative Contract Volumes (Details) - Commodity derivative [Member] MWh in Millions, Dth in Millions	Mar. 31, 2016 MWh Dth	Dec. 31, 2015 MWh Dth
Electricity purchases (in megawatt hours) [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | MWh	11	10
Electricity purchases (in megawatt hours) [Member] | MidAmerican Energy Company [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | MWh	0	15
Natural gas purchases (in decatherms) [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | Dth	360	317
Natural gas purchases (in decatherms) [Member] | MidAmerican Energy Company [Member]
Notional Amounts of Outstanding Derivative Positions [Line Items]
Derivative, nonmonetary notional amount | Dth	12	17