Fair Value Measurements - PacifiCorp (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
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	$ (27)	$ (29)
Assets, fair value disclosure	3,442	3,945
Derivative liability, fair value, gross asset and right to reclaim cash, offset	111	105
Derivative Liability	(105)	(83)
Cash collateral, net receivable, offset against derivative positions	84	76
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	2,820	3,296
Derivative Liability	0	(3)
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	535	565
Derivative Liability	(199)	(175)
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	114	113
Derivative Liability	(17)	(10)
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	(27)	(29)
Derivative assets	108	118
Derivative liability, fair value, gross asset and right to reclaim cash, offset	111	105
Derivative Liability	(97)	(75)
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	1
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	(3)
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	36	42
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(191)	(167)
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	98	104
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(17)	(10)
Money market mutual funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	413	685
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	413	685
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	185	178
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	185	178
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	42	51
PacifiCorp [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	36	42
PacifiCorp [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	12	13
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	0
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	77	74
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	4
Derivative assets	6	9
Derivative liability, fair value, gross asset and right to reclaim cash, offset	83	78
Derivative Liability	(54)	(39)
Cash collateral, net receivable, offset against derivative positions	77	74
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	12	13
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(137)	(117)
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	0
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	12	21
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	12	21
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	24	21
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	24	21
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