Unaudited Quarterly Operating Results (LLC) (Details) (MidAmerican Funding, LLC and Subsidiaries [Domain], USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
MidAmerican Funding, LLC and Subsidiaries [Domain]
Unaudited Quarterly Operating Results [Line Items]
Operating revenue	$ 836	$ 828	$ 709	$ 874	$ 853	$ 866	$ 805	$ 979	$ 3,247	$ 3,503	$ 3,815
Operating income	58	139	81	91	82	148	85	113	369	428	460
Net income	58	136	78	71	87	104	45	69	343	305	340
Net income attributable to MidAmerican Funding	58	136	77	71	87	104	44	69	342	304	340
Income tax benefits from tax method change	$ 18				$ 35