Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entities [Line Items]
Regulatory Assets: Current	$ 1,637	$ 1,796
Current Assets: Other	505	764
Other Noncurrent Assets: Regulatory assets	13,264	13,222
Property, Plant and Equipment: Cost	153,916	147,654
Accumulated depreciation and amortization	(48,185)	(45,773)
Other Noncurrent Assets: Other	3,539	3,289
Current Liabilities: Other	2,829	2,367
Current maturities of long-term debt	4,669	3,141
Long-Term Debt	56,049	54,985
Other Noncurrent Liabilities: AROs	12,912	12,437
Other Noncurrent Liabilities: Other	1,773	1,581
Duke Energy Florida
Variable Interest Entities [Line Items]
Regulatory Assets: Current	303	419
Current Assets: Other	25	58
Other Noncurrent Assets: Regulatory assets	1,821	2,194
Property, Plant and Equipment: Cost	21,662	20,457
Accumulated depreciation and amortization	(5,452)	(5,236)
Other Noncurrent Assets: Other	341	311
Current Liabilities: Other	359	415
Current maturities of long-term debt	623	571
Long-Term Debt	7,294	7,416
Other Noncurrent Liabilities: AROs	555	578
Other Noncurrent Liabilities: Other	205	136
DEFPF | Duke Energy Florida | VIE primary beneficiary
Variable Interest Entities [Line Items]
Receivables of VIEs	6	5
Regulatory Assets: Current	53	52
Current Assets: Other	16	39
Other Noncurrent Assets: Regulatory assets	951	989
Current Liabilities: Other	2	10
Current maturities of long-term debt	55	54
Long-Term Debt	1,001	1,057
Commercial Renewables | VIE primary beneficiary
Variable Interest Entities [Line Items]
Current Assets: Other	319	203
Property, Plant and Equipment: Cost	6,239	5,747
Accumulated depreciation and amortization	(1,200)	(1,041)
Other Noncurrent Assets: Other	79	106
Current maturities of long-term debt	161	162
Long-Term Debt	1,452	1,541
Other Noncurrent Liabilities: AROs	150	127
Other Noncurrent Liabilities: Other	$ 342	$ 228