Summary of Significant Accounting Policies Summary of Significant Accounting Policies - MEC - Income Taxes (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities, noncurrent		$ 7,346	$ 7,309
Regulatory assets		2,896	2,761
MidAmerican Energy Company [Member]
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities, noncurrent		1,620	1,661
Regulatory assets		273	204
Deferred Income Tax Charge [Member] | MidAmerican Energy Company [Member]
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities, noncurrent	[1]	$ 626	$ 681

[1] Amount predominantly represents the excess of nuclear decommission trust assets over the related asset retirement obligation. Refer to Note 11 for a discussion of asset retirement obligations.(4)