Income Taxes - MEC - Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 145	$ 185
Additions based on tax positions related to the current year	5	3
Additions for tax positions of prior years	6	13
Reductions for tax positions of prior years	(1)	(37)
Statute of limitations	(4)	(9)
Settlements	(1)	(5)
Interest and penalties	(1)	(5)
Ending balance	153	145
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	141	139
MidAmerican Energy Company [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	8	10
Additions based on tax positions related to the current year	4	5
Additions for tax positions of prior years	0	10
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	(3)	(5)
Reductions for tax positions of prior years	(1)	(12)
Ending balance	8	$ 8
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 26