Employee Benefit Plans - PacifiCorp - Utah Mine Disposition and Labor Agreement (Details) - Domestic Other Postretirement Plans [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	May 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Regulatory Deferrals, Before Tax	$ 7	$ 8
PacifiCorp [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amount To Be Transferred	150		$ 150
Defined Benefit Plan, Net Periodic Benefit Cost Not Yet Recognized, Regulatory Deferrals, Before Tax	$ 8	$ 9	$ 9