Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Reserves for legal matters	$ 61	$ 62
Duke Energy Carolinas
Loss Contingencies [Line Items]
Reserves for legal matters	3	2
Progress Energy
Loss Contingencies [Line Items]
Reserves for legal matters	52	55
Duke Energy Progress
Loss Contingencies [Line Items]
Reserves for legal matters	9	12
Duke Energy Florida
Loss Contingencies [Line Items]
Reserves for legal matters	23	22
Piedmont Natural Gas
Loss Contingencies [Line Items]
Reserves for legal matters	$ 1	$ 1

Amount of loss contingency liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant