Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	$ 1,109	$ 1,023
Other, current assets	433	458
Regulatory assets, noncurrent	13,367	12,878
Property, plant and equipment, cost	125,582	121,397
Accumulated depreciation and amortization	(41,161)	(39,406)
Current Liabilities: Other	1,734	2,044
Current maturities of long-term debt	2,485	2,319
Long-Term Debt	48,929	45,576
Deferred income taxes	15,058	14,155
Noncurrent Liabilities: Other	1,624	1,753
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	237	238
Other, current assets	27	37
Regulatory assets, noncurrent	3,077	3,159
Property, plant and equipment, cost	42,321	41,127
Accumulated depreciation and amortization	(14,969)	(14,365)
Current Liabilities: Other	435	468
Current maturities of long-term debt	705	116
Long-Term Debt	8,520	9,187
Deferred income taxes	6,796	6,544
Noncurrent Liabilities: Other	559	607
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	230	188
Other, current assets	40	57
Regulatory assets, noncurrent	3,588	3,243
Property, plant and equipment, cost	29,104	28,419
Accumulated depreciation and amortization	(10,793)	(10,561)
Current Liabilities: Other	318	365
Current maturities of long-term debt	203	452
Long-Term Debt	7,204	6,409
Deferred income taxes	3,606	3,323
Noncurrent Liabilities: Other	44	51
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	211	213
Other, current assets	154	125
Regulatory assets, noncurrent	2,850	2,480
Property, plant and equipment, cost	17,546	16,434
Accumulated depreciation and amortization	(4,960)	(4,644)
Current Liabilities: Other	310	352
Current maturities of long-term debt	567	326
Long-Term Debt	6,129	5,799
Deferred income taxes	3,076	2,694
Noncurrent Liabilities: Other	106	105
DEFPF [Member] \| Duke Energy Florida [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	6	6
Regulatory assets, current	51	50
Other, current assets	20	53
Regulatory assets, noncurrent	1,101	1,142
Current Liabilities: Other	3	17
Current maturities of long-term debt	53	62
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	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	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
Renewables [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Other, current assets	399	223
Property, plant and equipment, cost	3,923	3,419
Accumulated depreciation and amortization	(556)	(453)
Current maturities of long-term debt	162	198
Long-Term Debt	1,780	1,097
Deferred income taxes	223	275
Noncurrent Liabilities: Other	$ 247	$ 252

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