Income Taxes - MEC - Components of Net Deferred Income Tax Liability (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	$ 1,420	$ 1,610
AROs	304	306
Other	777	590
Total deferred income tax assets	3,178	3,081
Valuation allowances	(204)	(143)
Total deferred income tax assets, net	2,974	2,938
Property-related items	(10,816)	(10,439)
Regulatory assets	(785)	(631)
Other	(327)	(384)
Total deferred income tax liabilities	(14,749)	(12,591)
Net deferred income tax liability	(11,775)	(9,653)
MidAmerican Energy Company [Member]
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	288	368
AROs	229	234
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	42	26
Other	40	34
Total deferred income tax assets	651	713
Valuation allowances	(25)	(14)
Total deferred income tax assets, net	626	699
Property-related items	(3,583)	(3,253)
Regulatory assets	(97)	(68)
Other	0	(4)
Total deferred income tax liabilities	(3,680)	(3,325)
Net deferred income tax liability	(3,054)	(2,626)
Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards, State and Local	$ 52	$ 51