Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	$ 1,957	$ 2,005
Other, current assets	976	1,049
Regulatory assets, noncurrent	13,301	13,617
Property, plant and equipment, cost	139,377	134,458
Accumulated depreciation and amortization	(43,992)	(43,126)
Other noncurrent assets	2,969	2,935
Current Liabilities: Other	1,810	2,085
Current maturities of long-term debt	2,501	3,406
Long-Term Debt	53,681	51,123
Other Noncurrent Liabilities: Asset Retirement Obligations	12,256	9,548
Other Noncurrent Liabilities: Other	1,587	1,650
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	560	520
Other, current assets	31	72
Regulatory assets, noncurrent	3,429	3,457
Property, plant and equipment, cost	46,929	44,741
Accumulated depreciation and amortization	(15,899)	(15,496)
Other noncurrent assets	1,027	1,027
Current Liabilities: Other	415	571
Current maturities of long-term debt	7	6
Long-Term Debt	10,658	10,633
Other Noncurrent Liabilities: Asset Retirement Obligations	5,219	3,659
Other Noncurrent Liabilities: Other	645	671
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	622	703
Other, current assets	45	62
Regulatory assets, noncurrent	4,041	4,111
Property, plant and equipment, cost	33,188	31,459
Accumulated depreciation and amortization	(11,635)	(11,423)
Other noncurrent assets	627	612
Current Liabilities: Other	346	408
Current maturities of long-term debt	5	603
Long-Term Debt	8,893	7,451
Other Noncurrent Liabilities: Asset Retirement Obligations	5,471	4,311
Other Noncurrent Liabilities: Other	89	106
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	454	434
Other, current assets	55	46
Regulatory assets, noncurrent	2,316	2,454
Property, plant and equipment, cost	19,111	18,792
Accumulated depreciation and amortization	(5,003)	(4,968)
Other noncurrent assets	318	311
Current Liabilities: Other	426	406
Current maturities of long-term debt	470	270
Long-Term Debt	6,795	7,051
Other Noncurrent Liabilities: Asset Retirement Obligations	579	586
Other Noncurrent Liabilities: Other	95	93
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	5	5
Regulatory assets, current	52	52
Other, current assets	12	39
Regulatory assets, noncurrent	1,032	1,041
Current Liabilities: Other	2	10
Current maturities of long-term debt	54	53
Long-Term Debt	1,082	1,111
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	630	699
Long-Term Debt	475	450
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	495	547
Long-Term Debt	325	300
DEFR [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	317	357
Long-Term Debt	250	225
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	534	564
Long-Term Debt	350	325
Commercial Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Other, current assets	140	123
Property, plant and equipment, cost	4,018	4,007
Accumulated depreciation and amortization	(733)	(698)
Other noncurrent assets	280	261
Current maturities of long-term debt	173	174
Long-Term Debt	1,583	1,587
Other Noncurrent Liabilities: Asset Retirement Obligations	107	106
Other Noncurrent Liabilities: Other	$ 212	$ 212