Supplemental Cash Flow Disclosures - MidAmerican Funding (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Cash Flow Statements, Captions [Line Items]
Interest paid, net of amounts capitalized		$ 1,715	$ 1,673	$ 1,764
Income taxes received, net	[1]	540	1,016	1,666
Accruals related to property, plant and equipment additions		653	547	718
MidAmerican Funding, LLC and Subsidiaries [Domain]
Condensed Cash Flow Statements, Captions [Line Items]
Interest paid, net of amounts capitalized		218	204	177
Income taxes received, net		472	609	630
Accruals related to property, plant and equipment additions		224	131	249
Dividend, Noncash, Transfer Of Operations		$ 0	$ 90	$ 0

[1] Includes $636 million, $1.1 billion and $1.8 billion of income taxes received from Berkshire Hathaway in 2017, 2016 and 2015, respectively.