Commitments and Contingencies - Commitments Table (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) number_of_projects	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Contractual Obligation [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 143
Operating Leases, Future Minimum Payments, Due in Two Years	118
Operating Leases, Future Minimum Payments, Due in Three Years	95
Operating Leases, Future Minimum Payments, Due in Four Years	77
Operating Leases, Future Minimum Payments, Due in Five Years	66
Operating Leases, Future Minimum Payments, Due Thereafter	1,007
Operating Leases, Future Minimum Payments Due	1,506
Contractual Obligation, Due in Next Twelve Months	4,082
Contractual Obligation, Due in Second Year	2,167
Contractual Obligation, Due in Third Year	1,631
Contractual Obligation, Due in Fourth Year	1,497
Contractual Obligation, Due in Fifth Year	1,354
Contractual Obligation, Due after Fifth Year	11,311
Contractual Obligation	22,042
Operating Leases, Rent Expense	161	$ 146	$ 118
MidAmerican Funding [Member]
Contractual Obligation [Line Items]
Coal transportation costs, railroad	$ 185	$ 159	$ 174
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	$ 2,214
Purchase Obligation, Due in Second Year	1,760
Purchase Obligation, Due in Third Year	1,345
Purchase Obligation, Due in Fourth Year	1,229
Purchase Obligation, Due in Fifth Year	1,129
Purchase Obligation, Due after Fifth Year	9,494
Purchase Obligation	17,171
Capital Addition Purchase Commitments [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	1,544
Purchase Obligation, Due in Second Year	25
Purchase Obligation, Due in Third Year	11
Purchase Obligation, Due in Fourth Year	3
Purchase Obligation, Due in Fifth Year	3
Purchase Obligation, Due after Fifth Year	5
Purchase Obligation	1,591
Maintenance, service and other contracts [Member]
Contractual Obligation [Line Items]
Purchase Obligation, Due in Next Twelve Months	181
Purchase Obligation, Due in Second Year	264
Purchase Obligation, Due in Third Year	180
Purchase Obligation, Due in Fourth Year	188
Purchase Obligation, Due in Fifth Year	156
Purchase Obligation, Due after Fifth Year	805
Purchase Obligation	$ 1,774