Variable Interest Entities (Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Cash and cash equivalents	$ 1,424	$ 2,110	$ 1,670	$ 1,542
Restricted Receivables of VIEs	1,201	1,157
Intangibles, net	372	363
Restricted Other Assets of VIEs	62	135
Other Assets	2,399	2,231
Property, Plant and Equipment Cost, VIEs	1,558	913
Accumulated depreciation and amortization	(31,969)	(18,709)
Other Deferred Debits	178	153
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	2,444	1,433
Non-Recourse Notes Payable	312	273
Current Maturities of Long-Term Debt	3,110	1,894
Other Current Liabilities	2,511	1,091
Non-Recourse Long-Term Debt	852	949
Deferred income taxes	10,490	7,581
Asset Retirement Obligation	5,169	1,936
Other Liabilities	2,221	1,778
Noncontrolling interests	78	93
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Cash and cash equivalents	19	289	153	394
Restricted Receivables of VIEs	637	581
Other Current Assets	439	278
Other Assets	934	968
Accumulated depreciation and amortization	(11,437)	(11,269)
Other Deferred Debits	71	71
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	599	637
Current Maturities of Long-Term Debt	406	1,178
Other Current Liabilities	490	398
Non-Recourse Long-Term Debt	300	300
Deferred income taxes	5,181	4,555
Asset Retirement Obligation	1,959	1,846
Other Liabilities	924	926
Variable Interest Entity, Primary Beneficiary [Member] | Cinergy Receivables [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	534	547
Total Assets	534	547
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Non-Recourse Notes Payable	312	273
Total Liabilities	312	273
Net Assets of Consolidated VIEs	222	274
Variable Interest Entity, Primary Beneficiary [Member] | Cincap V [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	15	13
Other Current Assets	4	2
Restricted Other Assets of VIEs	52	65
Other Assets	10	14
Total Assets	81	94
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Current Maturities of Long-Term Debt	13	11
Other Current Liabilities	4	3
Non-Recourse Long-Term Debt	48	60
Other Liabilities	10	13
Total Liabilities	75	87
Net Assets of Consolidated VIEs	6	7
Variable Interest Entity, Primary Beneficiary [Member] | Renewables [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	16	13
Other Current Assets	133	124
Intangibles, net	12	12
Restricted Other Assets of VIEs	2	10
Other Assets		36
Property, Plant and Equipment Cost, VIEs	1,543	913
Accumulated depreciation and amortization	98	(62)
Other Deferred Debits	40	24
Total Assets	1,648	1,070
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	1	1
Taxes accrued	62	3
Current Maturities of Long-Term Debt	459	49
Other Current Liabilities	25	59
Non-Recourse Long-Term Debt	504	528
Deferred income taxes	154	160
Asset Retirement Obligation	23	13
Other Liabilities	39	37
Total Liabilities	1,267	850
Net Assets of Consolidated VIEs	381	220
Variable Interest Entity, Primary Beneficiary [Member] | Other Vies [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	(1)	3
Other Current Assets	2	8
Restricted Other Assets of VIEs		60
Other Assets	2
Property, Plant and Equipment Cost, VIEs	15
Accumulated depreciation and amortization	5
Other Deferred Debits		2
Total Assets	13	73
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable		1
Current Maturities of Long-Term Debt		5
Non-Recourse Long-Term Debt		61
Total Liabilities		67
Noncontrolling interests		1
Net Assets of Consolidated VIEs	13	5
Variable Interest Entity, Primary Beneficiary [Member] | Total Consolidated VIE {Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	1,201	1,157
Other Current Assets	139	134
Intangibles, net	12	12
Restricted Other Assets of VIEs	54	135
Other Assets	12	50
Property, Plant and Equipment Cost, VIEs	1,558	913
Accumulated depreciation and amortization	(103)	(62)
Other Deferred Debits	40	26
Total Assets	2,913	2,365
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Accounts payable	1	2
Non-Recourse Notes Payable	312	273
Taxes accrued	62	3
Current Maturities of Long-Term Debt	472	65
Other Current Liabilities	29	62
Non-Recourse Long-Term Debt	852	949
Deferred income taxes	154	160
Asset Retirement Obligation	23	13
Other Liabilities	49	50
Total Liabilities	1,954	1,577
Noncontrolling interests	0	1
Net Assets of Consolidated VIEs	959	787
Variable Interest Entity, Primary Beneficiary [Member] | Duke Energy Carolinas [Member] | Derf [Member]
Variable Interest Entity Consolidated Carrying Amount Assets [Abstract]
Restricted Receivables of VIEs	637	581
Total Assets	637	581
Variable Interest Entity Consolidated Carrying Amount Liabilities [Abstract]
Non-Recourse Long-Term Debt	300	300
Total Liabilities	300	300
Net Assets of Consolidated VIEs	$ 337	$ 281