Segment Information (LLC) (Details) (MidAmerican Funding, LLC and Subsidiaries [Domain], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 ReportableSegments		Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of Reportable Segments	3
Regulated electric	$ 415		$ 380
Regulated gas	315		263
Nonregulated	191		231
Total operating revenue	921		874
Depreciation and amortization	107		93
Total operating income	106		91
Assets	12,350	[1]		12,530	[1]
Regulated electric [Member]
Segment Reporting Information [Line Items]
Regulated electric	415		380
Depreciation and amortization	98		84
Total operating income	50		48
Assets	11,028	[1]		11,089	[1]
Regulated gas [Member]
Segment Reporting Information [Line Items]
Regulated gas	315		263
Depreciation and amortization	9		9
Total operating income	45		30
Assets	1,185	[1]		1,280	[1]
Nonregulated energy [Member]
Segment Reporting Information [Line Items]
Nonregulated	190		231
Total operating income	11		14
Assets	113	[1]		132	[1]
Other [Member]
Segment Reporting Information [Line Items]
Nonregulated	1		0
Total operating income	0		(1)
Assets	$ 24	[1]		$ 29	[1]

[1] (1)Total assets by reportable segment reflect the assignment of goodwill to applicable reporting units.