Fair Value Measurements - PacifiCorp (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash collateral, net receivable, offset against derivative positions	$ 85	$ 103
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross liability and obligation to return cash, offset	(18)	(16)
Assets, fair value disclosure	(3,228)	(2,692)
Derivative liability, fair value, gross asset and right to reclaim cash, offset	103	119
Derivative Liability	(198)	(237)
Cash collateral, net receivable, offset against derivative positions	85	103
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(2,620)	(2,173)
Derivative Liability	(5)	(13)
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(509)	(393)
Derivative Liability	(264)	(296)
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(117)	(142)
Derivative Liability	(32)	(47)
Commodity derivative [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross liability and obligation to return cash, offset	(18)	(16)
Derivative assets	93	93
Derivative liability, fair value, gross asset and right to reclaim cash, offset	103	119
Derivative Liability	(167)	(223)
Commodity derivative [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	1	0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(4)	(13)
Commodity derivative [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	22	16
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(234)	(283)
Commodity derivative [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	88	93
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(32)	(46)
Money market mutual funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	557	421
Money market mutual funds [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	557	421
Money market mutual funds [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Money market mutual funds [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Investment funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	174	136
Investment funds [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	174	136
Investment funds [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Trading Securities		0
Investment funds [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Trading Securities		0
PacifiCorp [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(220)	(37)
PacifiCorp [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(215)	(28)
PacifiCorp [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	(11)	(9)
PacifiCorp [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	(3)
PacifiCorp [Member] | Commodity derivative [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash collateral, net receivable, offset against derivative positions	73	75
PacifiCorp [Member] | Commodity derivative [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross liability and obligation to return cash, offset	(6)	(3)
Derivative assets	5	9
Assets, fair value disclosure	(6)	(3)
Derivative liability, fair value, gross asset and right to reclaim cash, offset	79	78
Derivative Liability	(37)	(70)
Cash collateral, net receivable, offset against derivative positions	73	75
PacifiCorp [Member] | Commodity derivative [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	0	0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
PacifiCorp [Member] | Commodity derivative [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	11	9
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(116)	(148)
PacifiCorp [Member] | Commodity derivative [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset including not subject to master netting arrangement	0	3
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
PacifiCorp [Member] | Money market mutual funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	199	13
PacifiCorp [Member] | Money market mutual funds [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	199	13
PacifiCorp [Member] | Money market mutual funds [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
PacifiCorp [Member] | Money market mutual funds [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
PacifiCorp [Member] | Investment funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	16	15
PacifiCorp [Member] | Investment funds [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	16	15
PacifiCorp [Member] | Investment funds [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0	0
PacifiCorp [Member] | Investment funds [Member] | Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	$ 0	$ 0