Summary of Significant Accounting Policies Summary of Significant Accounting Policies - MEC - Income Taxes (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets and Liabilities [Line Items]
Regulatory assets		$ 4,307	$ 4,155
MidAmerican Energy Company [Member]
Deferred Tax Assets and Liabilities [Line Items]
Regulatory assets		1,161	1,044
Deferred Income Tax Charge [Member] | MidAmerican Energy Company [Member]
Deferred Tax Assets and Liabilities [Line Items]
Regulatory assets	[1]	$ 985	$ 858

[1] (1)Amounts primarily represent income tax benefits related to state accelerated tax depreciation and certain property-related basis differences that were previously flowed through to customers and will be included in regulated rates when the temporary differences reverse.