Employee Benefit Plans - PacifiCorp - Multiemployer and Joint Trust Pension Plans (Details) - PacifiCorp [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Joint Trustee Plan, Percentage By Which Joint Trustee Plan was at Least Funded			0.00%		80.00%		80.00%
Joint Trustee Plan, Period Contributions	[1]	$ 7		$ 8		$ 8
UMWA Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans, Withdrawal Obligation, Most Recent Estimate		115
Multiemployer Plan, Contributions by Employer	[1]	$ 0		$ 0		$ 1
Multiemployer Plans, Certified Zone Status			Red		Red		Red

[1] PacifiCorp's and Energy West Mining Company's minimum contributions to the plans are based on the amount of wages paid to employees covered by the Local 57 Trust Fund collective bargaining agreements and the number of mining hours worked for the UMWA 1974 Pension Plan, respectively, subject to ERISA minimum funding requirements. As a result of the plan's critical status, Energy West Mining Company was required to begin paying a surcharge for hours worked on and after December 1, 2014.