Quarterly Financial Data (Unusual or Infrequently Occurring Items) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended							12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	$ (164)	$ (457)	$ (7)	$ (8)
Voluntary severance program expense				101
Goodwill impairment charge										175
Energy efficiency revenue adjustment					59	[1]
Pre-tax impairment charge								666	335	726
Total	(192)	(637)	(7)	(327)	59		(301)
Edwardsport IGCC Plant [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge	(28)	(180)		(420)			(222)
Emission Allowance [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge							(79)
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(46)	(184)	(5)	(4)
Voluntary severance program expense				101
Energy efficiency revenue adjustment					59	[2]
Pre-tax impairment charge								31	12	0
Total	(46)	(184)	(5)	97
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(82)	(217)	(20)	(7)
Pre-tax impairment charge								200	3	5
Replacement power refund		(100)
Refund to customers recorded as reduction to revenue					(288)
CVO mark-to-market							(59)
Total	(274)	(317)	(20)	(7)	(288)		(59)
Progress Energy [Member] | Crystal River Unit 3 Retirement [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge	(192)
Progress Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(36)	(180)	(12)	(4)
Pre-tax impairment charge								54	3	5
Progress Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(46)	(37)	(8)	(3)
Pre-tax impairment charge								146
Replacement power refund		(100)
Refund to customers recorded as reduction to revenue					(288)
Total	(238)	(137)	(8)	(3)
Progress Energy Florida [Member] | Crystal River Unit 3 Retirement [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge	(192)
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(12)	(22)	(1)	(1)
Goodwill impairment charge										237
Pre-tax impairment charge								2	89	837
Duke Energy Ohio [Member] | Emission Allowance [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge							(79)
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve the merger	(11)	(21)	(1)	(1)
Pre-tax impairment charge								579	234	44
Total	(39)	(201)	(1)	(421)
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member]
Quarterly Financial Information Disclosure [Line Items]
Pre-tax impairment charge	$ (28)	$ (180)		$ (420)			$ (222)

[1] In the fourth quarter of 2011, Duke Energy recorded $59 million of previously deferred revenue resulting from the receipt of an order from the NCUC which allowed the recognition of revenue in excess of amounts billed to customers.

[2] In the fourth quarter of 2011, Duke Energy Carolinas recorded $59 million of previously deferred revenue resulting from the receipt of an order from the NCUC which allowed the recognition of revenue in excess of amounts billed to customers.