Variable Interest Entities (Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Cash and cash equivalents	$ 1,296		$ 1,424		$ 1,071	$ 2,110
Restricted Receivables of VIEs	1,304		1,201
Other Current Assets	2,062		2,425
Intangibles, net	356		372
Restricted Other Assets of VIEs	54		62
Other Assets	2,466		2,399
Property, Plant and Equipment Cost, VIEs	1,579		1,558
Accumulated depreciation and amortization	(32,501)		(31,969)
Other Deferred Debits	196		178
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	1,985		2,444
Non-Recourse Notes Payable	325		312
Current Maturities of Long-Term Debt	3,323		3,110
Other Current Liabilities	2,068		2,511
Non-Recourse Long-Term Debt	1,255		852
Deferred income taxes	10,518		10,490
Asset Retirement Obligation	5,229		5,169
Other Liabilities	2,196		2,221
Noncontrolling interests	77		78
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	585		534
Total Assets	585		534
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Non-Recourse Notes Payable	325		312
Total Liabilities	325		312
Net Assets of Consolidated VIEs	260		222
CinCap V [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	16		15
Other Current Assets	5		4
Restricted Other Assets of VIEs	48		52
Other Assets	12		10
Total Assets	81		81
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Current Maturities of Long-Term Debt	13		13
Other Current Liabilities	6		4
Non-Recourse Long-Term Debt	44		48
Other Liabilities	11		10
Total Liabilities	74		75
Net Assets of Consolidated VIEs	7		6
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	23		16
Other Current Assets	208		133
Intangibles, net	11		12
Restricted Other Assets of VIEs	6		2
Other Assets	1
Property, Plant and Equipment Cost, VIEs	1,564		1,543
Accumulated depreciation and amortization	(114)		(98)
Other Deferred Debits	33		40
Total Assets	1,732		1,648
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	2		1
Taxes accrued	3		62
Current Maturities of Long-Term Debt	52		459
Other Current Liabilities	29		25
Non-Recourse Long-Term Debt	911		504
Deferred income taxes	275		154
Asset Retirement Obligation	23		23
Other Liabilities	33		39
Total Liabilities	1,328		1,267
Net Assets of Consolidated VIEs	404		381
Other VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	0		(1)
Other Current Assets	2		2
Other Assets	2		2
Property, Plant and Equipment Cost, VIEs	15		15
Accumulated depreciation and amortization	(5)		(5)
Total Assets	14		13
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Total Liabilities			0
Net Assets of Consolidated VIEs	14		13
Total Consolidated VIE [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	1,304		1,201
Other Current Assets	215		139
Intangibles, net	11		12
Restricted Other Assets of VIEs	54		54
Other Assets	15		12
Property, Plant and Equipment Cost, VIEs	1,579		1,558
Accumulated depreciation and amortization	(119)		(103)
Other Deferred Debits	33		40
Total Assets	3,092		2,913
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	2		1
Non-Recourse Notes Payable	325		312
Taxes accrued	3		62
Current Maturities of Long-Term Debt	65		472
Other Current Liabilities	35		29
Non-Recourse Long-Term Debt	1,255		852
Deferred income taxes	275		154
Asset Retirement Obligation	23		23
Other Liabilities	44		49
Total Liabilities	2,027		1,954
Noncontrolling interests	0
Net Assets of Consolidated VIEs	1,065		959
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Cash and cash equivalents	5		19		15	289
Restricted Receivables of VIEs	680		637
Other Current Assets	428		439
Other Assets	941		934
Accumulated depreciation and amortization	(11,663)		(11,437)
Other Deferred Debits	69		71
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	520		599
Current Maturities of Long-Term Debt	406		406
Other Current Liabilities	409		490
Non-Recourse Long-Term Debt	300		300
Deferred income taxes	5,281		5,181
Asset Retirement Obligation	1,990		1,959
Other Liabilities	912		924
Duke Energy Carolinas [Member] | DERF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	680	[1]	637	[2]
Total Assets	680	[1]	637	[2]
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Non-Recourse Long-Term Debt	300	[1]	300	[2]
Total Liabilities	300	[1]	300	[2]
Net Assets of Consolidated VIEs	$ 380	[1]	$ 337	[2]

[1] Duke Energy Receivables Finance Company, LLC (DERF) is a wholly owned limited liability company of Duke Energy Carolinas.

[2] DERF is a wholly owned limited liability company of Duke Energy Carolinas.