Investments in Unconsolidated Affiliates (Significant Subsidiaries) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments In Unconsolidated Affiliates [Line Items]
Current assets	$ 8,682	$ 9,163
Noncurrent assets	46,924	47,548
Current liabilities	16,305	14,752
Noncurrent liabilities	41,274	41,150
Membership interests	1,220	1,129
Operating loss	4,553	5,709	$ 4,685
Net income (loss)	1,082	3,571	2,644
Net (loss) income attributable to Duke Energy	1,377	3,748	2,666
Atlantic Coast Pipeline (ACP) | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Investments In Unconsolidated Affiliates [Line Items]
Current assets	43	17
Noncurrent assets	93	4,091
Current liabilities	1,965	37
Noncurrent liabilities	167	1,760
Membership interests	(1,996)	2,311
Net revenues	0
Operating loss	(4,612)	(5)	(6)
Net income (loss)	(4,512)	246	138
Net (loss) income attributable to Duke Energy	$ (2,121)	$ 116	$ 65