Related Party Transactions (Intercompany Income Taxes) (Details) - Affiliated Entity - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Duke Energy Carolinas
Related Party Transaction [Line Items]
Income tax payable	$ 44	$ 5
Progress Energy
Related Party Transaction [Line Items]
Income taxes receivable	114	125
Duke Energy Progress
Related Party Transaction [Line Items]
Income taxes receivable	1	28
Duke Energy Florida
Related Party Transaction [Line Items]
Income taxes receivable	4
Income tax payable		2
Duke Energy Ohio
Related Party Transaction [Line Items]
Income taxes receivable		9
Duke Energy Indiana
Related Party Transaction [Line Items]
Income taxes receivable		28
Income tax payable	6
Piedmont Natural Gas
Related Party Transaction [Line Items]
Income taxes receivable		$ 13
Income tax payable	$ 10

Carrying amount due within one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.5(c))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(a)(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_IncomeTaxesReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant