Employee Benefit Plans (Fair Value Measurements of Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	$ 50		$ 53
VEBA I [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	50		53
VEBA I [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	22		26
VEBA I [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	22		26
VEBA I [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	12		11
VEBA I [Member] | Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	12		11
VEBA I [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16		16
VEBA I [Member] | Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16		16
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	5,230	[1],[2]	4,842	[3],[4]
Net receivables and payables	26		27
Pending investment sales, net	29		3
Master Trust [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	43.00%		39.00%
Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2,690	[5],[6]	2,191	[7]
Net receivables and payables	43
Master Trust [Member] | Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	48.00%		50.00%
Master Trust [Member] | Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	44.00%		44.00%
Master Trust [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	9.00%		12.00%
Master Trust [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	12.00%		12.00%
Master Trust [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,421	[2]	2,058	[4]
Master Trust [Member] | Level 1 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	879	[6]	642	[7]
Master Trust [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	3,457	[2]	2,462	[4]
Master Trust [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,523	[6]	1,238	[7]
Master Trust [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	352	[2]	322	[4]
Master Trust [Member] | Level 3 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	288	[6]	311	[7]
Master Trust [Member] | U S Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	237	[1]	211	[3]
Master Trust [Member] | U S Government Securities [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	515	[5]	391
Master Trust [Member] | U S Government Securities [Member] | Level 1 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	405		247
Master Trust [Member] | U S Government Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	237		211
Master Trust [Member] | U S Government Securities [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	110		144
Master Trust [Member] | Government Bonds-Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	65	[1]	39	[3]
Master Trust [Member] | Government Bonds-Foreign [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	6	[5]
Master Trust [Member] | Government Bonds-Foreign [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	64		38
Master Trust [Member] | Government Bonds-Foreign [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	6
Master Trust [Member] | Government Bonds-Foreign [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1		1
Master Trust [Member] | Asset Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2	[1]	4	[3]
Master Trust [Member] | Asset Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2		3
Master Trust [Member] | Asset Backed Securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets			1
Master Trust [Member] | Real Estate Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	167	[1]	152	[3]
Master Trust [Member] | Real Estate Investment [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	167		152
Master Trust [Member] | Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	100	[1]	328	[3]
Master Trust [Member] | Short Term Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	23		276
Master Trust [Member] | Short Term Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	77		52
Master Trust [Member] | Government And Commercial Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	12	[1]	8	[3]
Master Trust [Member] | Government And Commercial Mortgage Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	12		8
Master Trust [Member] | Guaranteed Investment Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	37	[1]	39	[3]
Master Trust [Member] | Guaranteed Investment Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	37		39
Master Trust [Member] | Partnership Interest [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	141	[1]	127	[3]
Master Trust [Member] | Partnership Interest [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	154	[5]	153
Master Trust [Member] | Partnership Interest [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	141		127
Master Trust [Member] | Partnership Interest [Member] | Level 3 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	154		153
Master Trust [Member] | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,391	[1]	1,237	[3]
Master Trust [Member] | Corporate Bond Securities [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	432	[5]	407
Master Trust [Member] | Corporate Bond Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,388		1,236
Master Trust [Member] | Corporate Bond Securities [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	432		407
Master Trust [Member] | Corporate Bond Securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	3		1
Master Trust [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	4	[1]	7	[3]
Master Trust [Member] | Cash and Cash Equivalents [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	160	[5]	115
Master Trust [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	4		7
Master Trust [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	113		82
Master Trust [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	47		33
Master Trust [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2,993	[1]	2,568	[3]
Master Trust [Member] | Equity Securities [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,094	[5]	803
Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,415		1,745
Master Trust [Member] | Equity Securities [Member] | Level 1 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	361		313
Master Trust [Member] | Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,575		823
Master Trust [Member] | Equity Securities [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	733		490
Master Trust [Member] | Equity Securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	3
Master Trust [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	97	[1]	89	[3]
Master Trust [Member] | Hedge Funds [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	313	[5]	306
Master Trust [Member] | Hedge Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	97		89
Master Trust [Member] | Hedge Funds [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	189		159
Master Trust [Member] | Hedge Funds [Member] | Level 3 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124		147
Master Trust [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	(16)	[1],[8]	33	[3],[9]
Master Trust [Member] | Other Investments [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16	[5]	16
Master Trust [Member] | Other Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	(21)	[8]	30	[9]
Master Trust [Member] | Other Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	5	[8]	2	[9]
Master Trust [Member] | Other Investments [Member] | Level 2 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	6		5
Master Trust [Member] | Other Investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets			1	[9]
Master Trust [Member] | Other Investments [Member] | Level 3 [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	$ 10		$ 11

[1] Excludes $26 million in net receivables associated with security purchases and sales.

[2] Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 43%, 9% and 12% of the Duke Energy Master Trust assets at December 31, 2012, respectively. Accordingly, all Level 1, 2 and 3 amounts included in the table above are allocable to Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana using these percentages.

[3] Excludes $27 million in net receivables and payables associated with security purchases and sales.

[4] Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 39%, 12% and 12% of the Duke Energy Master Trust assets at December 31, 2012, respectively. Accordingly, all Level 1, 2 and 3 amounts included in the table above are allocable to Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana using these percentages.

[5] Excludes $43 million in net payables associated with security purchases and sales.

[6] Progress Energy Carolinas and Progress Energy Florida were allocated approximately 48% and 44% of the Progress Energy Master Trust assets at December 31, 2012, respectively. Accordingly, all Level 1, 2 and 3 amounts included in the table above are allocable to Progress Energy Carolinas and Progress Energy Florida using these percentages.

[7] Progress Energy Carolinas and Progress Energy Florida were allocated approximately 50% and 44% of the Progress Energy Master Trust assets at December 31, 2011, respectively. Accordingly, all Level 1, 2 and 3 amounts included in the table above are allocable to Progress Energy Carolinas and Progress Energy Florida using these percentages.

[8] Includes pending investment sales (net of investment purchases) of $29 million.

[9] Includes pending investment sales (net of investment purchases) of $3 million.