Commitments and Contingencies (Narrative 2) (Details) - Spent Nuclear Fuel Matters $ in Millions	Jun. 18, 2018 USD ($)
Duke Energy Progress
Gain Contingencies [Line Items]
Gain contingency, unrecorded amount	$ 100
Duke Energy Florida
Gain Contingencies [Line Items]
Gain contingency, unrecorded amount	$ 200

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

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