Employee Benefit Plans (MEC) Unrecognized Amounts (Details) (MidAmerican Energy Company and Subsidiaries [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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	$ 13
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	8
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss	121	111
Prior service costs (credit)	(4)	(4)
Total net periodic benefit cost not yet recognized	125	115	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	14	93
Defined Benefit Plan Net Amortization	(4)
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	10
Defined Benefit Plan, Amortization of Gains (Losses), Net	10
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	11
United States Pension Plans of US Entity, Defined Benefit [Member] | Regulatory Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	110	99	14
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	14	85
Defined Benefit Plan Net Amortization	(3)
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	11
United States Pension Plans of US Entity, Defined Benefit [Member] | Regulatory Liability [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	0	0	(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	0	1
Defined Benefit Plan Net Amortization	0
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	0
United States Pension Plans of US Entity, Defined Benefit [Member] | Receivables (Payables) with Affiliates [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	15	16	9
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	0	7
Defined Benefit Plan Net Amortization	(1)
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	(1)
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss	51	48
Prior service costs (credit)	53	58
Total net periodic benefit cost not yet recognized	(2)	(10)	(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	29
Defined Benefit Plan, Net Prior Service Cost (Credit) Arising During Period, Before Tax		(19)
Defined Benefit Plan Net Amortization	4	2
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	8	12
Defined Benefit Plan, Amortization of Gains (Losses), Net	3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit), Net	(6)
Defined Benefit Plan, Amounts That Will Be Amortized from Regulatory Assets (Liabilities) and Accumulated Other Comprehensive Income Loss In Next Fiscal Year	(3)
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member] | Regulatory Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	11	2	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	6	16
Defined Benefit Plan, Net Prior Service Cost (Credit) Arising During Period, Before Tax		(15)
Defined Benefit Plan Net Amortization	3	1
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	9	2
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member] | Regulatory Liability [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	0	0	(8)
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	0	8
Defined Benefit Plan, Net Prior Service Cost (Credit) Arising During Period, Before Tax		0
Defined Benefit Plan Net Amortization	0	0
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	0	8
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member] | Receivables (Payables) with Affiliates [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	(13)	(12)	(14)
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	(2)	5
Defined Benefit Plan, Net Prior Service Cost (Credit) Arising During Period, Before Tax		(4)
Defined Benefit Plan Net Amortization	1	1
Defined Benefit Plan, Before Adoption of FAS 158 Recognition Provisions, Net Periodic Benefit Cost Not Yet Recognized, Arising During Period, Before Tax	$ (1)	$ 2