Supplemental Cash Flow Disclosures - MEC (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income 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 Energy Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest paid, net of amounts capitalized		193	181	154
Income taxes received, net		465	601	629
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.