Risk Management and Hedging Activities (MEC) Not Designated as Hedging Contracts (Details) - MidAmerican Energy Company [Member] - Not Designated as Hedging Instrument [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
Regulatory Assets (Liabilities), Net, Derivatives [Roll Forward]
Beginning balance	$ 18	$ 32	$ 38	$ 10
Changes in fair value recognized in net regulatory assets	17	20	19	62
Net gains (losses) reclassified to operating revenue	(6)	(5)	(22)	(24)
Net gains (losses) reclassified to cost of gas sold	(1)	1	(7)	0
Ending balance	$ 28	$ 48	$ 28	$ 48