Segment Information (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 TheNumberOfReportableSegments	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Number of Reportable Segments									3
Regulated electric									$ 1,694	$ 1,662	$ 1,779
Regulated gas									659	769	852
Nonregulated									894	1,072	1,184
Total operating revenue	836	828	709	874	853	866	805	979	3,247	3,503	3,815
Total depreciation and amortization									392	336	344
Total operating income	58	139	81	91	82	148	85	113	369	428	460
Total fixed charges									162	176	190
Total income tax expense (benefit)									(108)	(26)	(61)
Total net income attributable to MidAmerican Funding									342	304	340
Total utility construction expenditures									645	565	337
Total assets	12,530				11,605				12,530	11,605	10,310
Regulated electric [Member]
Segment Reporting Information [Line Items]
Regulated electric									1,694	1,662	1,779
Total depreciation and amortization									356	301	309
Total operating income									270	294	319
Total fixed charges									123	133	136
Total income tax expense (benefit)									(129)	(61)	(84)
Total net income attributable to MidAmerican Funding									297	243	268
Total utility construction expenditures									588	505	295
Total assets	11,089				10,207				11,089	10,207	8,971
Regulated gas [Member]
Segment Reporting Information [Line Items]
Regulated gas									659	769	852
Total depreciation and amortization									36	35	35
Total operating income									47	66	64
Total fixed charges									15	18	18
Total income tax expense (benefit)									7	16	5
Total net income attributable to MidAmerican Funding									28	36	45
Total utility construction expenditures									57	60	42
Total assets	1,280				1,238				1,280	1,238	1,111
Nonregulated Energy [Member]
Segment Reporting Information [Line Items]
Nonregulated									889	1,070	1,179
Total operating income									53	69	76
Total income tax expense (benefit)									23	28	30
Total net income attributable to MidAmerican Funding									29	39	44
Total assets	132				135				132	135	197
Other [Member]
Segment Reporting Information [Line Items]
Nonregulated									5	2	5
Total operating income									(1)	(1)	1
Total fixed charges									24	25	36
Total income tax expense (benefit)									(9)	(9)	(12)
Total net income attributable to MidAmerican Funding									(12)	(14)	(17)
Total assets	$ 29				$ 25				$ 29	$ 25	$ 31