Employee Benefit Plans - MEC (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plan [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 6	$ 15	$ 18
Interest cost	26	29	78	87
Expected return on plan assets	(41)	(40)	(123)	(120)
Net amortization	8	7	23	22
Net periodic benefit cost	(2)	2	(7)	7
Pension Plan [Member] | Domestic Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	6	7
Interest cost	7	8	21	23
Expected return on plan assets	(11)	(11)	(33)	(33)
Net amortization	1	0	2	1
Net periodic benefit cost	(1)	(1)	(4)	(2)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	3	6	7
Interest cost	7	7	19	21
Expected return on plan assets	(9)	(9)	(31)	(30)
Net amortization	(3)	(3)	(9)	(10)
Net periodic benefit cost	(4)	(2)	(15)	(12)
Other Postretirement Benefits Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	4	4
Interest cost	2	3	6	7
Expected return on plan assets	(3)	(3)	(10)	(10)
Net amortization	(1)	(1)	(3)	(3)
Net periodic benefit cost	(1)	$ 1	(3)	$ (2)
Accounting Standards Update 2017-07 [Member] | Other Pension, Postretirement and Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior Period Reclassification Adjustment	16		8
Accounting Standards Update 2017-07 [Member] | Other Pension, Postretirement and Supplemental Plans [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior Period Reclassification Adjustment	(4)		(15)
Accounting Standards Update 2017-07 [Member] | MidAmerican Energy Company [Member] | Other Pension, Postretirement and Supplemental Plans [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior Period Reclassification Adjustment	$ (4)		$ (14)