Short-Term Debt and Credit Facilities - MEC - Credit Facility (Details) $ in Millions		Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	$ 9,051	$ 6,345
Short-term Debt	[1]	(4,488)	(1,869)
Line of Credit Facility, Amounts Supported	[1]	(594)	(457)
Line of Credit Facility, Remaining Borrowing Capacity	[1]	3,969	4,019
MidAmerican Energy Company [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		905	605
Short-term Debt		0	(99)
Line of Credit Facility, Amounts Supported		(370)	(220)
Line of Credit Facility, Remaining Borrowing Capacity		$ 535	$ 286
MidAmerican Energy Company [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Debt to capitalization ratio		0.65
MidAmerican Energy Company [Member] | Commercial Paper [Member]
Line of Credit Facility [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time			0.73%
Regulatory Approval for Additional Short-Term Debt Issuances		$ 905
MidAmerican Energy Company [Member] | Unsecured credit facility, $900 million, expiring March 2020 [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		900
MidAmerican Energy Company [Member] | Unsecured 364-day Credit Facility, $5 million, expiring June [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 5

[1] (1)The table does not include unused credit facilities and letters of credit for investments that are accounted for under the equity method.