Income Taxes (Net Deferred Income Tax Liability Components) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	$ 2,948	$ 790
Tax credit carryforwards	3,311	930
Other	408	137
Valuation allowance	(226)	(144)
Net deferred income tax assets	6,441	1,713
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(1,093)	(809)
Accelerated depreciation rates	(11,208)	(6,989)
Regulatory assets and deferred debits	(3,819)	(1,219)
Total deferred income tax liabilities	(16,120)	(9,017)
Total net deferred income tax liabilities	(9,679)	(7,304)
Duke Energy Carolinas [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	194	228
Tax credit carryforwards	447	199
Other	22	18
Net deferred income tax assets	663	445
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(838)	(720)
Accelerated depreciation rates	(4,289)	(3,576)
Regulatory assets and deferred debits	(627)	(658)
Total deferred income tax liabilities	(5,754)	(4,954)
Total net deferred income tax liabilities	(5,091)	(4,509)
Progress Energy [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	822	900
Tax credit carryforwards	1,536	1,163
Regulatory liabilities and deferred credits		375
Other	230	522
Valuation allowance	(77)	(71)
Net deferred income tax assets	2,511	2,889
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(112)
Accelerated depreciation rates	(2,803)	(3,098)
Regulatory assets and deferred debits	(1,775)	(1,271)
Other		(315)
Total deferred income tax liabilities	(4,690)	(4,684)
Total net deferred income tax liabilities	(2,179)	(1,795)
Progress Energy Carolinas [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	342	441
Tax credit carryforwards	309	57
Regulatory liabilities and deferred credits		142
Other	82	168
Net deferred income tax assets	733	808
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(108)	(103)
Accelerated depreciation rates	(2,178)	(1,908)
Regulatory assets and deferred debits	(465)	(541)
Other		(17)
Total deferred income tax liabilities	(2,751)	(2,569)
Total net deferred income tax liabilities	(2,018)	(1,761)
Progress Energy Florida [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	333	513
Tax credit carryforwards	91	42
Regulatory liabilities and deferred credits		198
Other	126	101
Net deferred income tax assets	550	854
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(6)	(56)
Accelerated depreciation rates	(592)	(1,180)
Regulatory assets and deferred debits	(1,318)	(685)
Other		(120)
Total deferred income tax liabilities	(1,916)	(2,041)
Total net deferred income tax liabilities	(1,366)	(1,187)
Duke Energy Ohio [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	52	68
Tax credit carryforwards	152
Investments and other assets		3
Other	10	31
Valuation allowance	(1)
Net deferred income tax assets	213	102
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(25)
Accelerated depreciation rates	(1,823)	(1,706)
Regulatory assets and deferred debits	(197)	(216)
Total deferred income tax liabilities	(2,045)	(1,922)
Total net deferred income tax liabilities	(1,832)	(1,820)
Duke Energy Indiana [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	115	92
Tax credit carryforwards	340	95
Other	27	5
Net deferred income tax assets	482	192
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(18)	(2)
Accelerated depreciation rates	(1,131)	(968)
Regulatory assets and deferred debits	(185)	(136)
Total deferred income tax liabilities	(1,334)	(1,106)
Total net deferred income tax liabilities	$ (852)	$ (914)