Income Taxes - MEC - Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 198	$ 220
Additions based on tax positions related to the current year	7	3
Additions for tax positions of prior years	6	46
Reductions for tax positions of prior years	(11)	(58)
Statute of limitations	(1)	(6)
Settlements	(67)	(6)
Interest and penalties	(4)	(1)
Ending balance	128	198
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	104	163
MidAmerican Energy Company [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	10	26
Additions based on tax positions related to the current year	0	3
Additions for tax positions of prior years	10	47
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	(2)	(6)
Reductions for tax positions of prior years	(8)	(46)
Statute of limitations	0	(5)
Settlements	0	(6)
Interest and penalties	0	(3)
Ending balance	10	$ 10
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 29