Summary of Significant Accounting Policies - PacifiCorp - Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 37
Ending balance	31	$ 37
PacifiCorp [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	7	8
Ending balance	7	7	$ 8
Allowance for Doubtful Accounts [Member] | PacifiCorp [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	7	8	9
Charged to operating costs and expenses, net	10	11	13
Write-offs, net	$ 10	12	14
Ending balance		$ 7	$ 8