Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,715	$ 1,409
Taxes accrued	521	577
Current Liabilities: Other	2,020	2,085
Deferred income taxes	8,532	7,806
Other Noncurrent Liabilities: Other	1,583	1,650
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,305	1,060
Total assets	1,305	1,060
Taxes accrued	(2)	(1)
Current Liabilities: Other	4	4
Deferred income taxes	48	21
Other Noncurrent Liabilities: Other	11	12
Total liabilities	61	36
Net assets	1,244	1,024
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,066	822
Total assets	1,066	822
Taxes accrued	(2)	(1)
Deferred income taxes	48	21
Total liabilities	46	20
Net assets	1,020	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	52	48
Total assets	52	48
Current Liabilities: Other	4	4
Other Noncurrent Liabilities: Other	11	12
Total liabilities	15	16
Net assets	37	32
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	50	114
Taxes accrued	135	202
Current Liabilities: Other	76	74
Deferred income taxes	872	817
Other Noncurrent Liabilities: Other	94	93
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	45	93
Total assets	45	93
Net assets	45	93
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	83	122
Taxes accrued	25	43
Current Liabilities: Other	120	107
Deferred income taxes	1,084	1,009
Other Noncurrent Liabilities: Other	14	16
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	81	118
Total assets	81	118
Net assets	$ 81	$ 118