Income Taxes - MEC - Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 181	$ 128
Additions based on tax positions related to the current year	4	6
Additions for tax positions of prior years	38	70
Reductions for tax positions of prior years	(38)	(18)
Statute of limitations	2	(4)
Settlements	(2)	(1)
Ending balance	185	181
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	154	158
MidAmerican Energy Company [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	12	10
Additions based on tax positions related to the current year	4	1
Additions for tax positions of prior years	47	23
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	(4)	(4)
Reductions for tax positions of prior years	(48)	(19)
Interest and penalties	(1)	1
Ending balance	10	$ 12
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 29