Commitments and Contingencies - Commitments Table (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) number_of_projects	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Contractual Obligation [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 180
Operating Leases, Future Minimum Payments, Due in Two Years	157
Operating Leases, Future Minimum Payments, Due in Three Years	141
Operating Leases, Future Minimum Payments, Due in Four Years	121
Operating Leases, Future Minimum Payments, Due in Five Years	111
Operating Leases, Future Minimum Payments, Due Thereafter	1,297
Operating Leases, Future Minimum Payments Due	2,007
Contractual Obligation, Due in Next Twelve Months	3,644
Contractual Obligation, Due in Second Year	2,100
Contractual Obligation, Due in Third Year	1,819
Contractual Obligation, Due in Fourth Year	1,562
Contractual Obligation, Due in Fifth Year	1,419
Contractual Obligation, Due after Fifth Year	12,396
Contractual Obligation	22,940
Operating Leases, Rent Expense	156	$ 156	$ 146
MidAmerican Funding [Member]
Contractual Obligation [Line Items]
Coal transportation costs, railroad	$ 109	$ 137	$ 185
Number of Construction Projects | number_of_projects	4
Fuel, capacity and transmission contract commitments [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	$ 2,098
Purchase Obligation, Due in Second Year	1,637
Purchase Obligation, Due in Third Year	1,435
Purchase Obligation, Due in Fourth Year	1,210
Purchase Obligation, Due in Fifth Year	1,055
Purchase Obligation, Due after Fifth Year	10,044
Purchase Obligation	17,479
Capital Addition Purchase Commitments [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	1,120
Purchase Obligation, Due in Second Year	57
Purchase Obligation, Due in Third Year	5
Purchase Obligation, Due in Fourth Year	0
Purchase Obligation, Due in Fifth Year	0
Purchase Obligation, Due after Fifth Year	0
Purchase Obligation	1,182
Maintenance, service and other contracts [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	246
Purchase Obligation, Due in Second Year	249
Purchase Obligation, Due in Third Year	238
Purchase Obligation, Due in Fourth Year	231
Purchase Obligation, Due in Fifth Year	253
Purchase Obligation, Due after Fifth Year	1,055
Purchase Obligation	$ 2,272