Risk Management and Hedging Activities (MEC) Collateral and Contingent Features (Details) - MidAmerican Energy Company [Member] - Commodity Contract [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative [Line Items]
Derivatives, net liability positions with specific credit-risk features, aggregate fair value	$ 60		$ 60		$ 52
Collateral already posted, aggregate fair value	0		0		0
Additional collateral, aggregate fair value	$ 52		52		$ 36
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Cash flow hedge ineffectiveness is immaterial	insignificant	insignificant
Gain (loss) on cash flow hedge ineffectiveness, net			$ 1	$ 0