Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Variable Interest Entities [Line Items]
Regulatory Assets: Current	$ 1,791	$ 1,641
Current Assets: Other	768	462
Other Noncurrent Assets: Regulatory assets	12,247	12,421
Property, Plant and Equipment: Cost	160,652	155,580
Accumulated depreciation and amortization	(50,543)	(48,827)
Other Noncurrent Assets: Other	3,686	3,601
Current Liabilities: Other	2,239	2,936
Current maturities of long-term debt	4,873	4,238
Long-Term Debt	57,929	55,625
Other Noncurrent Liabilities: AROs	12,278	12,286
Other Noncurrent Liabilities: Other	1,714	1,719
Duke Energy Florida
Variable Interest Entities [Line Items]
Regulatory Assets: Current	365	265
Current Assets: Other	35	41
Other Noncurrent Assets: Regulatory assets	1,829	1,799
Property, Plant and Equipment: Cost	23,300	22,123
Accumulated depreciation and amortization	(5,839)	(5,560)
Other Noncurrent Assets: Other	351	335
Current Liabilities: Other	403	374
Current maturities of long-term debt	276	823
Long-Term Debt	7,273	7,092
Other Noncurrent Liabilities: AROs	443	514
Other Noncurrent Liabilities: Other	265	209
DEFPF | Duke Energy Florida | VIE primary beneficiary
Variable Interest Entities [Line Items]
Receivables of VIEs	6	4
Regulatory Assets: Current	54	53
Current Assets: Other	17	39
Other Noncurrent Assets: Regulatory assets	896	937
Current Liabilities: Other	2	10
Current maturities of long-term debt	56	55
Long-Term Debt	946	1,002
Commercial Renewables | VIE primary beneficiary
Variable Interest Entities [Line Items]
Current Assets: Other	330	257
Property, Plant and Equipment: Cost	7,315	6,394
Accumulated depreciation and amortization	(1,414)	(1,242)
Other Noncurrent Assets: Other	110	67
Current maturities of long-term debt	165	167
Long-Term Debt	1,552	1,569
Other Noncurrent Liabilities: AROs	167	148
Other Noncurrent Liabilities: Other	$ 341	$ 316