Employee Benefit Plans Employee Benefit Plans - PacifiCorp (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Pension, Postretirement and Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior Period Reclassification Adjustment	$ 4
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	$ 2
Interest cost	6	6
Expected return on plan assets	(10)	(10)
Net amortization	(3)	(3)
Net periodic benefit cost	(5)	(5)
PacifiCorp [Member] | Other Pension, Postretirement and Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior Period Reclassification Adjustment	6
PacifiCorp [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Interest cost	3	3
Expected return on plan assets	5	6
Net amortization	(1)	(1)
Net periodic benefit cost	(3)	(3)
Domestic Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	6
Interest cost	26	29
Expected return on plan assets	(41)	(40)
Net amortization	8	7
Net periodic benefit cost	(2)	2
Domestic Plan [Member] | PacifiCorp [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	11	12
Expected return on plan assets	18	18
Net amortization	3	4
Net periodic benefit cost	$ (4)	$ (2)