Income Taxes Income Taxes - MEC - Tax Reform (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory income tax rate		35.00%	35.00%	35.00%
Deferred Tax Liabilities, Net		$ 8,242	$ 13,879
Regulatory Liabilities		$ 7,511	$ 3,120
MidAmerican Energy Company [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory income tax rate		35.00%	35.00%	35.00%
Deferred Tax Liabilities, Net		$ 2,237	$ 3,572
Deferred Income Tax Charge [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liabilities	[1]	$ 4,143	$ 25
Tax Cuts and Jobs Act of 2017 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory income tax rate		21.00%
Deferred Tax Liabilities, Net	[2]	$ 7,115
Tax Cuts and Jobs Act of 2017 [Member] | MidAmerican Energy Company [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory income tax rate		21.00%
Deferred Tax Liabilities, Net	[2]	$ 1,824
Tax Cuts and Jobs Act of 2017 [Member] | Deferred Income Tax Charge [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liabilities	[2]	5,950
Tax Cuts and Jobs Act of 2017 [Member] | Deferred Income Tax Charge [Member] | MidAmerican Energy Company [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liabilities	[2]	$ 1,845

[1] (1)Amounts primarily represent income tax liabilities related to the federal tax rate change from 35% to 21% that are probable to be passed on to customers, offset by income tax benefits related to certain property-related basis differences and other various differences that were previously passed on to customers and will be included in regulated rates when the temporary differences reverse. See Note 11 for further discussion of 2017 Tax Reform impacts.

[2] (1)Amounts primarily represent income tax liabilities related to the federal tax rate change from 35% to 21% that are probable to be passed on to customers, offset by income tax benefits related to accelerated tax depreciation and certain property-related basis differences that were previously passed on to customers and will be included in regulated rates when the temporary differences reverse. See Note 10 for further discussion of 2017 Tax Reform impacts.