Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	$ 1,723	$ 2,005
Other, current assets	1,333	1,049
Regulatory assets, noncurrent	13,916	13,617
Property, plant and equipment, cost	143,794	134,458
Accumulated depreciation and amortization	(45,149)	(43,126)
Other noncurrent assets	2,905	2,935
Current Liabilities: Other	2,074	2,085
Current maturities of long-term debt	3,096	3,406
Long-Term Debt	54,818	51,123
Other Noncurrent Liabilities: Asset retirement obligations	11,740	9,548
Other Noncurrent Liabilities: Other	1,649	1,650
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	573	520
Other, current assets	19	72
Regulatory assets, noncurrent	3,587	3,457
Property, plant and equipment, cost	47,815	44,741
Accumulated depreciation and amortization	(16,359)	(15,496)
Other noncurrent assets	1,061	1,027
Current Liabilities: Other	545	571
Current maturities of long-term debt	457	6
Long-Term Debt	11,001	10,633
Other Noncurrent Liabilities: Asset retirement obligations	5,184	3,659
Other Noncurrent Liabilities: Other	617	671
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	515	703
Other, current assets	95	62
Regulatory assets, noncurrent	4,363	4,111
Property, plant and equipment, cost	33,594	31,459
Accumulated depreciation and amortization	(11,761)	(11,423)
Other noncurrent assets	595	612
Current Liabilities: Other	416	408
Current maturities of long-term debt	306	603
Long-Term Debt	8,593	7,451
Other Noncurrent Liabilities: Asset retirement obligations	5,038	4,311
Other Noncurrent Liabilities: Other	105	106
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	367	434
Other, current assets	42	46
Regulatory assets, noncurrent	2,370	2,454
Property, plant and equipment, cost	19,887	18,792
Accumulated depreciation and amortization	(5,148)	(4,968)
Other noncurrent assets	307	311
Current Liabilities: Other	423	406
Current maturities of long-term debt	621	270
Long-Term Debt	6,511	7,051
Other Noncurrent Liabilities: Asset retirement obligations	572	586
Other Noncurrent Liabilities: Other	102	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	7	5
Regulatory assets, current	52	52
Other, current assets	16	39
Regulatory assets, noncurrent	1,002	1,041
Current Liabilities: Other	2	10
Current maturities of long-term debt	54	53
Long-Term Debt	1,056	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	775	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	564	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	471	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	505	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	172	123
Property, plant and equipment, cost	5,160	4,007
Accumulated depreciation and amortization	(996)	(698)
Other noncurrent assets	63	261
Current maturities of long-term debt	177	174
Long-Term Debt	1,604	1,587
Other Noncurrent Liabilities: Asset retirement obligations	125	106
Other Noncurrent Liabilities: Other	$ 218	$ 212