Joint Ownership (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Duke Energy Carolinas Catawba Nuclear Station (Units 1 and 2) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	19.25%
Property, Plant, and Equipment	$ 900
Accumulated Depreciation	467
Construction Work in Progress	6
Progress Energy Carolinas Mayo Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	83.83%
Property, Plant, and Equipment	807
Accumulated Depreciation	292
Construction Work in Progress	65
Progress Energy Carolinas Shearon Harris Nuclear Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	83.83%
Property, Plant, and Equipment	3,571
Accumulated Depreciation	1,985
Construction Work in Progress	104
Progress Energy Carolinas Brunswick Nuclear Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	81.67%
Property, Plant, and Equipment	1,842
Accumulated Depreciation	985
Construction Work in Progress	98
Progress Energy Carolinas Roxboro Station (Unit 4) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	87.06%
Property, Plant, and Equipment	741
Accumulated Depreciation	474
Construction Work in Progress	15
Progress Energy Florida Crystal River Nuclear Station (Unit 3) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	91.78%
Property, Plant, and Equipment	0
Accumulated Depreciation	0
Construction Work in Progress	0
Progress Energy Florida Intercession City Station (Unit P11) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	66.67%
Property, Plant, and Equipment	24
Accumulated Depreciation	13
Construction Work in Progress	1
Duke Energy Ohio Miami Fort Station (Units 7 and 8) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	64.00%
Property, Plant, and Equipment	617
Accumulated Depreciation	212
Construction Work in Progress	4
Duke Energy Ohio W.C. Beckjord Station (Unit 6) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	37.50%
Property, Plant, and Equipment	0
Accumulated Depreciation	0
Construction Work in Progress	0
Duke Energy Ohio J.M. Stuart Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	39.00%
Property, Plant, and Equipment	820
Accumulated Depreciation	265
Construction Work in Progress	13
Duke Energy Ohio Conesville Station (Unit 4) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	40.00%
Property, Plant, and Equipment	296
Accumulated Depreciation	54
Construction Work in Progress	27
Duke Energy Ohio W.M. Zimmer Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	46.50%
Property, Plant, and Equipment	1,354
Accumulated Depreciation	552
Construction Work in Progress	3
Duke Energy Ohio Killen Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	33.00%
Property, Plant, and Equipment	310
Accumulated Depreciation	142
Construction Work in Progress	2
Duke Energy Ohio Transmission [Member]
Jointly Owned Utility Plant Interests [Line Items]
Property, Plant, and Equipment	96
Accumulated Depreciation	48
Construction Work in Progress	0
Duke Energy Kentucky East Bend Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	69.00%
Property, Plant, and Equipment	445
Accumulated Depreciation	231
Construction Work in Progress	9
Duke Energy Indiana Gibson Station (Unit 5) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	50.05%
Property, Plant, and Equipment	305
Accumulated Depreciation	149
Construction Work in Progress	6
Duke Energy Indiana Vermillion [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	62.50%
Property, Plant, and Equipment	153
Accumulated Depreciation	56
Construction Work in Progress	0
Duke Energy Indiana Transmission and local facilities [Member]
Jointly Owned Utility Plant Interests [Line Items]
Property, Plant, and Equipment	3,517
Accumulated Depreciation	1,521
Construction Work in Progress	0
International Energy Brazil-Canoas I and II [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Share	47.20%
Property, Plant, and Equipment	305
Accumulated Depreciation	89
Construction Work in Progress	$ 0