Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 676	$ 857	$ 960	$ 2,036
Restricted receivables of VIEs	1,943	1,748
Regulatory Assets, Current	825	877
Other current assets	451	327
Regulatory Assets, Noncurrent	11,290	11,373
Investments and other assets	2,972	3,042
Property, plant and equipment, cost	115,143	112,826
Accumulated depreciation and amortization	(38,412)	(37,665)
Other deferred debits	30	43
Accounts payable	2,221	2,400
Current maturities of long-term debt	2,342	2,074
Other current liabilities	1,784	2,115
Long-Term Debt	39,931	37,495
Deferred income taxes	13,038	12,705
Asset retirement obligation	10,231	10,264
Other liabilities	1,730	1,706
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	16	13	28	13
Restricted receivables of VIEs	696	596
Regulatory Assets, Current	262	305
Other current assets	86	128
Regulatory Assets, Noncurrent	2,856	2,766
Investments and other assets	916	999
Property, plant and equipment, cost	40,285	39,398
Accumulated depreciation and amortization	(13,880)	(13,521)
Other deferred debits	3	4
Accounts payable	565	753
Current maturities of long-term debt	468	356
Other current liabilities	400	519
Long-Term Debt	8,592	7,711
Deferred income taxes	6,472	6,146
Asset retirement obligation	3,910	3,918
Other liabilities	645	621
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	8	15	13	9
Restricted receivables of VIEs	421	349
Regulatory Assets, Current	187	264
Other current assets	35	121
Regulatory Assets, Noncurrent	2,744	2,710
Investments and other assets	509	486
Property, plant and equipment, cost	27,771	27,313
Accumulated depreciation and amortization	(10,350)	(10,141)
Other deferred debits	2	3
Accounts payable	300	399
Current maturities of long-term debt	252	2
Other current liabilities	314	412
Long-Term Debt	6,163	6,366
Deferred income taxes	3,167	3,027
Asset retirement obligation	4,594	4,567
Other liabilities	23	45
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	8	8	$ 13	$ 8
Restricted receivables of VIEs	355	308
Regulatory Assets, Current	135	98
Other current assets	43	21
Regulatory Assets, Noncurrent	2,553	2,725
Investments and other assets	288	292
Property, plant and equipment, cost	15,938	15,343
Accumulated depreciation and amortization	(4,730)	(4,720)
Other deferred debits	3	2
Accounts payable	390	322
Current maturities of long-term debt	48	13
Other current liabilities	361	452
Long-Term Debt	5,492	4,253
Deferred income taxes	2,571	2,460
Asset retirement obligation	792	802
Other liabilities	103	146
DEFPF [Member] | Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory Assets, Current	34
Other current assets	7
Regulatory Assets, Noncurrent	1,194
Current maturities of long-term debt	35
Long-Term Debt	1,243
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	300	254
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	225	225
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	325	325
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Other current assets	223	138
Property, plant and equipment, cost	2,578	2,015
Accumulated depreciation and amortization	(376)	(321)
Current maturities of long-term debt	154	108
Long-Term Debt	866	968
Deferred income taxes	31	289
Other liabilities	$ 277	$ 33