Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,409	$ 1,175	$ 925
Investments and other assets	2,935	2,960
Other current liabilities	2,085	1,865
Deferred income taxes	7,806	6,621
Other Liabilities	1,650	1,581
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	1,060	919
Investments and other assets		17
Total assets	1,060	936
Taxes accrued	(1)	(29)
Other current liabilities	4	4
Deferred income taxes	21	42
Other Liabilities	12	12
Total liabilities	36	29
Net assets of non-consolidated VIEs	1,024	907
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	822	697
Investments and other assets		17
Total assets	822	714
Taxes accrued	(1)	(29)
Deferred income taxes	21	42
Total liabilities	20	13
Net assets of non-consolidated VIEs	802	701
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	48	42
Total assets	48	42
Other current liabilities	4	4
Other Liabilities	12	12
Total liabilities	16	16
Net assets of non-consolidated VIEs	32	26
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	190	180
Total assets	190	180
Net assets of non-consolidated VIEs	190	180
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	114	133
Investments and other assets	41	21
Other current liabilities	74	71
Deferred income taxes	817	781
Other Liabilities	93	108
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	93	87
Total assets	93	87
Net assets of non-consolidated VIEs	93	87
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	122	125
Investments and other assets	194	189
Other current liabilities	107	104
Deferred income taxes	1,009	925
Other Liabilities	16	18
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	118	106
Total assets	118	106
Net assets of non-consolidated VIEs	$ 118	$ 106