Income Taxes (LLC) Net Unrecognized Tax Benefits (Details) (MidAmerican Funding, LLC and Subsidiaries [Domain], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
MidAmerican Funding, LLC and Subsidiaries [Domain]
Net Unrecognized Tax Benefits [Line Items]
Unrecognized tax benefits that would impact the effective tax rate	$ 37	$ 47
Reconciliation of Net Unrecognized Tax Benefits [Roll Forward]
Beginning balance	47	80
Additions based on tax positions related to current year	10	8
Additions for tax positions of prior years	25	4
Reductions based on tax positions related to the current year	(16)	(2)
Reductions for tax positions of prior years	(22)	(41)
Statute of limitations	(4)	(1)
Settlements	(2)	0
Interest and penalties	(1)	(1)
Ending balance	$ 37	$ 47