Segment Information Segment Information - MidAmerican Funding (Details) $ in Millions		3 Months Ended
		Mar. 31, 2018 USD ($) OperatingSegments ReportableSegments	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | OperatingSegments		8
Revenues		$ 4,440	$ 4,166
Operating income		871	967
Interest expense		(466)	(458)
Capitalized interest		12	10
Allowance for equity funds		21	17
Other, net		30	26
Income before income tax (benefit) expense and equity income		285	591
Assets		$ 90,912		$ 90,208
MidAmerican Funding, LLC and Subsidiaries [Domain]
Segment Reporting Information [Line Items]
Number of reportable segments | ReportableSegments		2
Electric Domestic Regulated Revenue		$ 469	433
Revenues		747	696
Operating income		79	102
Interest expense		(63)	(59)
Capitalized interest		4	2
Allowance for equity funds		10	6
Other, net		10	11
Income before income tax (benefit) expense and equity income		40	62
Assets	[1]	17,879		17,621
MidAmerican Funding, LLC and Subsidiaries [Domain] | Regulated Electric [Member]
Segment Reporting Information [Line Items]
Electric Domestic Regulated Revenue		469	433
Operating income		36	63
Assets	[1]	16,445		16,105
MidAmerican Funding, LLC and Subsidiaries [Domain] | Regulated Gas [Member]
Segment Reporting Information [Line Items]
Gas Domestic Regulated Revenue		275	262
Operating income		43	39
Assets	[1]	1,402		1,482
MidAmerican Funding, LLC and Subsidiaries [Domain] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Other Revenue, Net		3	$ 1
Assets	[1]	$ 32		$ 34

[1] (1)Consists principally of cash and cash equivalents not included in either the regulated electric or regulated natural gas segments.