Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,602	$ 1,409
Taxes accrued	470	577
Current Liabilities: Other	1,810	2,085
Deferred income taxes	8,040	7,806
Other Noncurrent Liabilities: Other	1,587	1,650
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,235	1,060
Total assets	1,235	1,060
Taxes accrued	(1)	(1)
Current Liabilities: Other	2	4
Deferred income taxes	40	21
Other Noncurrent Liabilities: Other	11	12
Total liabilities	52	36
Net assets	1,183	1,024
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	998	822
Total assets	998	822
Taxes accrued	(1)	(1)
Deferred income taxes	40	21
Total liabilities	39	20
Net assets	959	802
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	187	190
Total assets	187	190
Net assets	187	190
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	50	48
Total assets	50	48
Current Liabilities: Other	2	4
Other Noncurrent Liabilities: Other	11	12
Total liabilities	13	16
Net assets	37	32
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	79	114
Taxes accrued	157	202
Current Liabilities: Other	69	74
Deferred income taxes	842	817
Other Noncurrent Liabilities: Other	79	93
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	67	93
Total assets	67	93
Net assets	67	93
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	102	122
Taxes accrued	63	43
Current Liabilities: Other	92	107
Deferred income taxes	1,050	1,009
Other Noncurrent Liabilities: Other	29	16
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	89	118
Total assets	89	118
Net assets	$ 89	$ 118