Risk Management and Hedging Activities (MEC) Collateral and Contingent Features (Details) (MidAmerican Energy Company and Subsidiaries [Member], Commodity Contract [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
MidAmerican Energy Company and Subsidiaries [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	$ 84	$ 122
Collateral Already Posted, Aggregate Fair Value	0	0
Additional Collateral, Aggregate Fair Value	$ 72	$ 109