Jointly Owned Utility Facilities - PacifiCorp (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 9,730
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	4,205
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	153
PacifiCorp [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	4,336
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	1,779
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 112
PacifiCorp [Member] | Jim Bridger Unit Nos 1 thru 4 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	67.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 1,420
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	583
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 10
PacifiCorp [Member] | Hunter Unit No 1 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	94.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 473
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	161
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 1
PacifiCorp [Member] | Hunter No. 2 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	60.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 296
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	98
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0
PacifiCorp [Member] | Wyodak [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	80.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 467
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	203
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 1
PacifiCorp [Member] | Colstrip Unit Nos 3 and 4 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	10.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 244
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	130
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 5
PacifiCorp [Member] | Hermiston [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 178
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	76
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 2
PacifiCorp [Member] | Craig Units Nos 1 and 2 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	19.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 325
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	223
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 32
PacifiCorp [Member] | Hayden Unit No 1 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	25.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 74
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	32
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0
PacifiCorp [Member] | Hayden No. 2 [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	13.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 43
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	20
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0
PacifiCorp [Member] | Foote Creek [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	79.00%
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 39
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	25
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0
PacifiCorp [Member] | Transmission and distribution facilities
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Percentage Share	Various
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 777
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	228
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 61