Variable Interest Entities (Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 358	$ 392	$ 383	$ 463
Regulatory Assets, Current	1,437	1,023
Other current assets	634	458
Property, plant and equipment, cost	127,507	121,397
Accumulated depreciation and amortization	(41,537)	(39,406)
Regulatory assets, noncurrent	12,442	12,878
Investments and other assets	2,960	2,769
Accounts payable	3,043	2,994
Current maturities of long-term debt	3,244	2,319
Other current liabilities	1,865	2,044
Long-Term debt	49,035	45,576
Deferred income taxes	6,621	14,155
Asset retirement obligations	9,486	10,200
Other Liabilities	1,581	1,753
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	16	14	13	13
Regulatory Assets, Current	299	238
Other current assets	19	37
Property, plant and equipment, cost	42,939	41,127
Accumulated depreciation and amortization	(15,063)	(14,365)
Regulatory assets, noncurrent	2,853	3,159
Investments and other assets	979	943
Accounts payable	842	833
Current maturities of long-term debt	1,205	116
Other current liabilities	486	468
Long-Term debt	8,598	9,187
Deferred income taxes	3,413	6,544
Asset retirement obligations	3,273	3,673
Other Liabilities	566	607
Duke Energy Progress [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	20	11	15	9
Regulatory Assets, Current	352	188
Other current assets	97	57
Property, plant and equipment, cost	29,583	28,419
Accumulated depreciation and amortization	(10,903)	(10,561)
Regulatory assets, noncurrent	3,507	3,243
Investments and other assets	599	525
Accounts payable	402	589
Current maturities of long-term debt	3	452
Other current liabilities	376	365
Long-Term debt	7,204	6,409
Deferred income taxes	1,883	3,323
Asset retirement obligations	4,378	4,508
Other Liabilities	45	51
Duke Energy Florida [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	13	16	$ 8	$ 8
Regulatory Assets, Current	389	213
Other current assets	86	125
Property, plant and equipment, cost	17,730	16,434
Accumulated depreciation and amortization	(4,947)	(4,644)
Regulatory assets, noncurrent	2,503	2,480
Investments and other assets	284	278
Accounts payable	602	413
Current maturities of long-term debt	768	326
Other current liabilities	334	352
Long-Term debt	6,327	5,799
Deferred income taxes	1,761	2,694
Asset retirement obligations	742	778
Other Liabilities	108	105
DEFPF [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	4	6
Regulatory Assets, Current	51	50
Other current assets	40	53
Regulatory assets, noncurrent	1,091	1,142
Current maturities of long-term debt	53	62
Other current liabilities	10	17
Long-Term debt	1,164	1,217
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	450	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	300
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
Commercial Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Other current assets	174	223
Property, plant and equipment, cost	3,923	3,419
Accumulated depreciation and amortization	(591)	(453)
Current maturities of long-term debt	170	198
Long-Term debt	1,700	1,097
Deferred income taxes	(148)	275
Other Liabilities	$ 241	$ 252