Supplemental Cash Flow Disclosures - MEC (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Cash and cash equivalents		$ 1,290	$ 1,040
Restricted cash and cash equivalents		140	212
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		1,445	1,268	$ 883	$ 1,283
Interest paid, net of amounts capitalized		1,855	1,723	1,713
Income taxes received, net	[1]	1,361	850	780
Accrued capital expenditures		801	888	823
MidAmerican Energy Company [Member]
Condensed Income Statements, Captions [Line Items]
Cash and cash equivalents		38	287
Restricted cash and cash equivalents		7	43
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		45	330	56	$ 282
Interest paid, net of amounts capitalized		286	224	198
Income taxes received, net		709	450	494
Accrued capital expenditures		$ 227	$ 337	$ 371

[1] Includes $1,504 million, $942 million and $884 million of income taxes received from Berkshire Hathaway in 2020, 2019 and 2018, respectively.