Income Taxes - MEC - Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 220	$ 211
Additions based on tax positions related to the current year	3	11
Additions for tax positions of prior years	46	48
Reductions for tax positions of prior years	(58)	(50)
Statute of limitations	(6)	(1)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	6	0
Interest and penalties	(1)	1
Ending balance	198	220
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	163	188
MidAmerican Energy Company [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	26	29
Additions based on tax positions related to the current year	3	6
Additions for tax positions of prior years	47	38
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	(6)	(4)
Reductions for tax positions of prior years	(46)	(40)
Statute of limitations	(5)	(3)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	6	0
Interest and penalties	3	0
Ending balance	10	$ 26
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 26