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, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
MidAmerican Energy Company [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Regulatory Assets (Liabilities), Net, Derivatives [Roll Forward]
Beginning balance	$ 45	$ 73
Changes in fair value recognized in net regulatory assets	(1)	10
Net gains reclassified to operating revenue	3	13
Net gains reclassified to cost of fuel, energy and capacity	0	1
Net losses reclassified to cost of gas sold	(23)	(37)
Ending balance	$ 24	$ 60