Employee Benefit Plans Employee Benefit Plans - PacifiCorp - Employer Contributions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contributions in current fiscal year	$ 5
Employer contributions	5
PacifiCorp [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contributions in current fiscal year	0
Employer contributions	0
Domestic Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contributions in current fiscal year	15
Employer contributions	9
Domestic Plan [Member] | PacifiCorp [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contributions in current fiscal year	5
Employer contributions	$ 3