Regulatory Matters - MEC - Regulatory Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets		$ 2,761	$ 4,307
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided		$ 1,100	2,800
Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory asset amortization period years	[1]	Various
Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory asset amortization period years		13.1467065868263
Employee benefit plans [Member]
Regulatory Assets [Line Items]
Regulatory asset amortization period years	[2]	15.7540740740741
Unrealized loss on regulated derivative contracts [Member]
Regulatory Assets [Line Items]
Regulatory asset amortization period years		4
MidAmerican Energy Company [Member]
Regulatory Assets [Line Items]
Regulatory assets		$ 204	1,161
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided		200	1,200
MidAmerican Energy Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory assets	[3]	$ 0	985
MidAmerican Energy Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period	[4]	10 years
Regulatory assets	[4]	$ 133	105
MidAmerican Energy Company [Member] | Employee benefit plans [Member]
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period	[5]	13 years
Regulatory assets	[5]	$ 38	40
MidAmerican Energy Company [Member] | Unrealized loss on regulated derivative contracts [Member]
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Regulatory assets		$ 6	2
MidAmerican Energy Company [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets [Line Items]
Regulatory asset amortization period years		Various
Regulatory assets		$ 27	$ 29

[1] Amounts primarily represent 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.

[2] (1)Represents amounts not yet recognized as a component of net periodic benefit cost that are expected to be included in regulated rates when recognized.

[3] (1)Amounts primarily represent income tax benefits related to state 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.

[4] (2)Amount predominantly relates to asset retirement obligations for fossil-fueled and wind-powered generating facilities. Refer to Note 12 for a discussion of asset retirement obligations.

[5] (3)Represents amounts not yet recognized as a component of net periodic benefit cost that are expected to be included in regulated rates when recognized.