Employee Benefit Plans - MEC - Unrecognized Amounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Amortization of Gains (Losses), Net	$ 33
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(16)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	15
MidAmerican Energy Company [Member]
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Amortization of Gains (Losses), Net	2
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(4)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	(2)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Gains (Losses), Before Tax	14	$ 88
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Prior Service Cost (Credit), Before Tax	(37)	(52)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(16)	43	$ 37
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	73	(6)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	14	(12)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(59)	6
Defined Benefit Plan, Amortization of Gains (Losses), Net	1
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(15)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	(13)
Other Postretirement Benefits Plan [Member] | Regulatory Asset, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	10	55	49
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(52)	(5)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	7	(11)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(45)	6
Other Postretirement Benefits Plan [Member] | Regulatory Liability, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(26)	(12)	(12)
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	21	(1)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	(7)	(1)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(14)	0
Other Postretirement Benefits Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Gains (Losses), Before Tax	23	36
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Prior Service Cost (Credit), Before Tax	(25)	(31)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(2)	5	6
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(11)	(5)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	4	4
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(7)	(1)
Defined Benefit Plan, Amortization of Gains (Losses), Net	1
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(5)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	(4)
Other Postretirement Benefits Plan [Member] | MidAmerican Energy Company [Member] | Regulatory Asset, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	14	18	17
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(7)	(2)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	3	3
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(4)	1
Other Postretirement Benefits Plan [Member] | MidAmerican Energy Company [Member] | Receivables (Payables) With Affiliates [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(16)	(13)	(11)
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(4)	(3)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	1	1
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(3)	(2)
Domestic Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Gains (Losses), Before Tax	649	775
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Prior Service Cost (Credit), Before Tax	(3)	(7)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	642	761	741
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	94	(65)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	25	46
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(119)	20
Defined Benefit Plan, Amortization of Gains (Losses), Net	32
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(1)	(1)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	28
Domestic Plan [Member] | Pension Plan [Member] | Regulatory Asset, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	665	761	729
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(68)	76
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	(28)	45
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(96)	32
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net		(1)
Domestic Plan [Member] | Pension Plan [Member] | Regulatory Liability, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(43)	(13)	(1)
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	29	(11)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	1	(1)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(30)	(12)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net		0
Domestic Plan [Member] | Pension Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Gains (Losses), Before Tax	(11)	15
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Net Prior Service Cost (Credit), Before Tax	1	1
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(10)	16	28
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(24)	(10)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	(2)	(2)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(26)	(12)
Defined Benefit Plan, Amortization of Gains (Losses), Net	1
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	1
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	2
Domestic Plan [Member] | Pension Plan [Member] | MidAmerican Energy Company [Member] | Regulatory Asset, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	24	22	22
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	4	1
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	(2)	(1)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	2	0
Domestic Plan [Member] | Pension Plan [Member] | MidAmerican Energy Company [Member] | Regulatory Liability, Pension and Other Postretirement Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	(41)	(12)	0
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	(29)	(11)
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	0	(1)
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(29)	(12)
Domestic Plan [Member] | Pension Plan [Member] | MidAmerican Energy Company [Member] | Receivables (Payables) With Affiliates [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Before Tax	7	6	$ 6
Defined Benefit Plan, Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Defined Benefit Plan, Net Unamortized Gain (Loss) Arising During Period, Before Tax	1	0
Defined Benefit Plan, Net Amortization Recognized in Net Periodic Benefit Cost Before Tax	0	0
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	$ 1	$ 0