Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,864	$ 1,409
Taxes accrued	712	577
Current Liabilities: Other	2,074	2,085
Deferred income taxes	8,776	7,806
Other Noncurrent Liabilities: Other	1,649	1,650
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,442	1,060
Total assets	1,442	1,060
Taxes accrued	(2)	(1)
Current Liabilities: Other	3	4
Deferred income taxes	57	21
Other Noncurrent Liabilities: Other	11	12
Total liabilities	69	36
Net assets	1,373	1,024
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,152	822
Total assets	1,152	822
Taxes accrued	(2)	(1)
Deferred income taxes	57	21
Total liabilities	55	20
Net assets	1,097	802
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	235	190
Total assets	235	190
Net assets	235	190
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	55	48
Total assets	55	48
Current Liabilities: Other	3	4
Other Noncurrent Liabilities: Other	11	12
Total liabilities	14	16
Net assets	41	32
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	63	114
Taxes accrued	162	202
Current Liabilities: Other	74	74
Deferred income taxes	901	817
Other Noncurrent Liabilities: Other	95	93
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	48	93
Total assets	48	93
Net assets	48	93
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	85	122
Taxes accrued	29	43
Current Liabilities: Other	107	107
Deferred income taxes	1,119	1,009
Other Noncurrent Liabilities: Other	57	16
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	76	118
Total assets	76	118
Net assets	$ 76	$ 118