Risk Management and Hedging Activities (MEC) Not Designated As Hedging Contracts (Details) (MidAmerican Energy Company and Subsidiaries [Member], Commodity Contract [Member], Not Designated as Hedging Instrument [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
MidAmerican Energy Company and Subsidiaries [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Regulatory Assets (Liabilities), Net, Derivatives [Roll Forward]
Beginning balance	$ 73	$ 27	$ (14)
Changes in fair value recognized in regulatory assets (liabilities)	14	76	23
Net gains reclassified to operating revenue	21	0	16
Net gains reclassified to cost of fuel, energy and capacity	2	8	18
Net losses reclassified to cost of gas sold	(65)	(38)	(16)
Ending balance	$ 45	$ 73	$ 27