Regulatory Matters (Narrative) (Details) $ in Millions																																			1 Months Ended					3 Months Ended				9 Months Ended		12 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 30, 2019 USD ($)	Oct. 11, 2019	Sep. 30, 2019 USD ($) customer	Sep. 09, 2019 USD ($)	Sep. 03, 2019 USD ($)	Aug. 13, 2019 USD ($)	Jul. 02, 2019 USD ($)	Jun. 13, 2019 USD ($)	May 29, 2019 USD ($)	May 21, 2019 USD ($)	Apr. 02, 2019 USD ($)	Apr. 01, 2019 USD ($)	Mar. 25, 2019 USD ($)	Jan. 30, 2019 USD ($)	Dec. 27, 2018 USD ($)	Nov. 08, 2018 USD ($)	Oct. 30, 2018 USD ($)	Aug. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)	Jun. 22, 2018 USD ($)	May 31, 2018 USD ($)	Apr. 13, 2018 USD ($)	Feb. 28, 2018	Feb. 15, 2018 USD ($)	Nov. 22, 2017	Sep. 27, 2017 USD ($)	Sep. 26, 2017 USD ($)	Aug. 25, 2017 USD ($)	Jun. 01, 2017 USD ($)	Jun. 30, 2016	Dec. 22, 2015	Jan. 05, 2015	Sep. 02, 2014	Sep. 30, 2019 USD ($) customer	Nov. 30, 2018 USD ($)	May 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2019 USD ($) customer	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) customer MW	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 16, 2019 USD ($)	Jul. 12, 2019 USD ($)	Apr. 30, 2019 USD ($)	Mar. 28, 2019 USD ($)	Jan. 28, 2019 USD ($)	Oct. 31, 2018 customer	Sep. 28, 2018 USD ($)	Sep. 30, 2017 customer	Oct. 31, 2015 USD ($)
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								$ 1,484		$ 1,584		$ 4,337	$ 4,592
Loss before income taxes																																								(1,511)		(1,230)		(3,388)	(2,640)
Generation facilities to be retired, net				$ 267																															$ 267					267	$ 362			267
Public utilities, property, plant and equipment, net				98,912																															98,912					98,912	91,694			98,912
Regulated operating revenue, electric, non-nuclear																																								6,515		6,216		17,223	16,678
Impairment charges																																								(20)		124		$ (16)	339
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW																																												5,002
Public utilities, property, plant and equipment, net				3,193																															3,193					3,193				$ 3,193
Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																																		47.00%
Long-term purchase commitment, period																																		20 years
Investment amount				$ 1,100																															$ 1,100					$ 1,100				$ 1,100
Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage				24.00%																															24.00%					24.00%				24.00%
Estimated contributions				$ 229																															$ 229					$ 229				$ 229
Equity method investment, OTTI																																													55
Dominion Resources [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																																		48.00%
Southern Company Gas [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																																		5.00%
Williams Partners L.P. [Member] | Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage				41.00%																															41.00%					41.00%				41.00%
Minimum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost				$ 7,300																															$ 7,300					$ 7,300				$ 7,300
Maximum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost				$ 7,800																															$ 7,800					$ 7,800				$ 7,800
Hurricane Florence, Hurricane Michael And Winter Storm Diego Damages [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other												$ 553
Estimated capital cost												96
Credit Facility [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Percentage of outstanding borrowings				47.00%																															47.00%					47.00%				47.00%
Atlantic Coast Pipeline [Member] | Financial Guarantee [Member]
Public Utilities, General Disclosures [Line Items]
Maximum potential amount of future payments associated with guarantees				$ 802																															$ 802					$ 802				$ 802
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								443		514		1,324	1,464
Loss before income taxes																																								(708)		(641)		(1,439)	(1,204)
Public utilities, property, plant and equipment, net				31,456																															31,456					31,456	29,245			31,456
Impairment charges																																								6		1		11	191
Duke Energy Carolinas [Member] | Generation Facilities Evaluated For Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net				732																															732					732				732
Duke Energy Carolinas [Member] | Hurricane Florence, Hurricane Michael And Winter Storm Diego Damages [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other												171
Estimated capital cost												20
Duke Energy Carolinas [Member] | 2017 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																											$ 4
Utilities operating expense																					$ 150
Penalty assessed																					70
Reduction of annual recovery of deferred coal ash costs																					$ 14
Requested rate increase (decrease), amount																													$ 647
Requested rate increase, percentage																													13.60%
Requested return on equity, percent																								9.90%
Public utilities, requested equity capital structure, percentage																								52.00%
Public utilities, requested debt capital structure, percentage																								48.00%
Regulatory asset, amortization period																					5 years
Loss before income taxes																																											14
Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																	$ 168
Requested rate increase, percentage																	10.00%
Public utilities, approved equity capital structure, percentage											53.00%
Public utilities, approved debt capital structure, percentage											47.00%
Approved return on equity percentage											9.50%
Change in tax rate, deferred tax liability, income tax benefit											$ 66						$ 66
Measurement period adjustment, income tax expense (benefit)											45						46
Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Recovery costs denied											115
Regulatory assets											$ 96						$ 242
Regulatory asset, amortization period											5 years						5 years
Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member] | Deferred Project Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets											$ 125
Regulatory asset, amortization period											12 years
Duke Energy Carolinas [Member] | FERC Formula Rate Matter [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Customer refundable fees, refund payments																									$ 25
Duke Energy Carolinas [Member] | 2018 Sale of Hydro Plants [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																																															$ 32
Estimated loss on asset sale																																					$ 40
Duke Energy Carolinas [Member] | 2019 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount				$ 291
Requested rate increase, percentage				6.00%
Requested rate increase (decrease), gross amount				$ 445
Requested rate increase (decrease), rider reduction				154
Duke Energy Carolinas [Member] | State and Local Jurisdiction [Member] | North Carolina Department of Revenue [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
State and local taxes, increase (reduction), amount											$ (17)						$ (17)
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								378		431		1,070	1,187
Loss before income taxes																																								(326)		(272)		(775)	(652)
Generation facilities to be retired, net				267																															267					267	362			267
Public utilities, property, plant and equipment, net				22,100																															22,100					22,100	20,398			22,100
Impairment charges																																													33
Duke Energy Progress [Member] | Generation Facilities Evaluated For Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net				1,200																															1,200					1,200				$ 1,200
Duke Energy Progress [Member] | Asheville Plant [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW																																												376
Generation facilities to be retired, net				234																															234					234	327			$ 234
Duke Energy Progress [Member] | Hurricane Florence, Hurricane Michael And Winter Storm Diego Damages [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other												382
Estimated capital cost												$ 76
Duke Energy Progress [Member] | 2017 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																														$ 477
Requested rate increase, percentage																														14.90%
Requested return on equity, percent																										9.90%
Public utilities, requested equity capital structure, percentage																										52.00%
Public utilities, requested debt capital structure, percentage																										48.00%
Requested rate increase (decrease), amended amount																														$ 420
Requested rate increase (decrease) amended, percentage																														13.00%
Loss before income taxes																																											$ 68
Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																	$ 59
Requested rate increase, percentage																	10.30%
Public utilities, approved equity capital structure, percentage											53.00%
Public utilities, approved debt capital structure, percentage											47.00%
Approved return on equity percentage											9.50%
Change in tax rate, deferred tax liability, income tax benefit											$ 17						$ 17
Measurement period adjustment, income tax expense (benefit)											12						10
Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Recovery costs denied											65
Regulatory assets											$ 4						$ 51
Regulatory asset, amortization period											5 years						5 years
Duke Energy Progress [Member] | Western Carolinas Modernization Plan [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost																																																		$ 893
Regulatory asset, amortization period																																												10 years
Duke Energy Progress [Member] | Hurricane Dorian Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Estimated storm costs - O&M				208																															208					208				$ 208
Estimated storm costs - capital investments				10																															10					10				10
Duke Energy Progress [Member] | Hurricane Dorian Storm Damage [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets				$ 182																															$ 182					$ 182				$ 182
Duke Energy Progress [Member] | State and Local Jurisdiction [Member] | North Carolina Department of Revenue [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
State and local taxes, increase (reduction), amount											$ 12						$ 12
Duke Energy Progress [Member] | Subsequent Event [Member] | FERC Complaint [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Agreement return on equity			11.00%
Duke Energy Progress [Member] | Subsequent Event [Member] | 2019 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ 464
Requested rate increase, percentage		12.30%
Requested rate increase (decrease), gross amount		$ 586
Requested rate increase (decrease), rider reduction		120
Requested rate increase (decrease), rider reduction, TCJA and return deferred revenue		$ 122
Duke Energy Progress [Member] | North Carolina [Member] | Hurricane Dorian Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers experiencing outages | customer				270,000																															270,000					270,000				270,000
Duke Energy Progress [Member] | South Carolina [Member] | Hurricane Dorian Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers experiencing outages | customer				30,000																															30,000					30,000				30,000
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								$ 256		245		$ 730	719
Loss before income taxes																																								(346)		(286)		(715)	(614)
Public utilities, property, plant and equipment, net				$ 14,739																															$ 14,739					14,739	13,824			14,739
Impairment charges																																								(25)		1		(25)	1
Duke Energy Florida [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets				80																															80					80	217			80
Duke Energy Florida [Member] | Citrus County Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital costs																																									1,600														$ 1,500
Impairment charges																																									60
Reversal of impairment charges																																			25
Duke Energy Florida [Member] | Storm Restoration Cost Recovery [Member]
Public Utilities, General Disclosures [Line Items]
Customers experiencing outages | customer																																																						1,000,000
Operation, maintenance and other									$ 6
Decrease in storm reserve									24
Allowed storm reserve																						$ 132															132
Property, plant and equipment, net									$ 18
Duke Energy Florida [Member] | Storm Restoration Cost Recovery [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Estimated storm costs - capital and operation maintenance																						510															510														$ 508
Duke Energy Florida [Member] | Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers experiencing outages | customer																																																				72,000
Estimated storm costs - capital and operation maintenance				360																															360					360				360					$ 221
Property, plant and equipment, net				85																															85					85	35			85
Duke Energy Florida [Member] | Hurricane Dorian Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Estimated storm costs - capital and operation maintenance				153																															153					153				153
Duke Energy Florida [Member] | Federal Tax Act Impacts [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Tax act annual savings																$ 4						134
Tax act excess deferred tax amortization requested rate decrease, amount																71						67
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																						201
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | FPSC [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																$ 155						151															151
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | Crystal River Units 3 and 4 [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net																						$ 50															$ 50
Duke Energy Florida [Member] | 2017 Second Revised and Restated Stipulation and Settlement Agreement [Member] | Hamilton Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease), amount																		$ 15
Duke Energy Florida [Member] | 2017 Second Revised and Restated Stipulation and Settlement Agreement [Member] | Columbia Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																				$ 14
Duke Energy Florida [Member] | 2017 Second Revised and Restated Stipulation and Settlement Agreement [Member] | Trenton Generation Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount														$ 13
Duke Energy Florida [Member] | 2017 Second Revised and Restated Stipulation and Settlement Agreement [Member] | Lake Placid Generation Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount														8
Duke Energy Florida [Member] | 2017 Second Revised and Restated Stipulation and Settlement Agreement [Member] | DeBary Solar Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount														$ 11
Duke Energy Florida [Member] | Noncurrent Assets, Other [Member] | Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Estimated storm costs - capital and operation maintenance				220																															220					220	165			220
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								123		76		378	337
Loss before income taxes																																								(85)		(119)		(224)	(144)
Public utilities, property, plant and equipment, net				7,208																															7,208					7,208	6,643			7,208
Regulated operating revenue, electric, non-nuclear																																								408		373		1,099	1,055
Duke Energy Ohio [Member] | Ohio Base Rate Case 2017 [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																																						$ 15
Requested return on equity, percent																																						10.40%
Public utilities, requested equity capital structure, percentage																							50.75%
Public utilities, requested debt capital structure, percentage																							49.25%
Approved rate increase (decrease), amount																							$ (20)
Requested rate increase (decrease), amended amount																							$ (19)
Requested rate increase (decrease) amended, percentage																							9.84%
Duke Energy Ohio [Member] | Ohio Base Rate Case 2017 [Member] | PUCO [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																												$ (18)
Requested return on equity, percent																												9.22%
Duke Energy Ohio [Member] | Ohio Base Rate Case 2017 [Member] | PUCO [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																												$ (29)
Requested return on equity, percent																												10.24%
Requested Rider Revenue Increase																							$ 10
Duke Energy Ohio [Member] | Energy Efficiency Cost Recovery [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulated operating revenue, electric, non-nuclear																																							$ 20
Duke Energy Ohio [Member] | Energy Efficiency Cost Recovery [Member] | PUCO [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease), amount																											$ 38
Approved rate increase (decrease), one-time waiver amount																																														$ 56
Duke Energy Ohio [Member] | Natural Gas Pipeline Extension [Member] | OPSB [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost excluding AFUDC				163																															163					163				163
Duke Energy Ohio [Member] | Natural Gas Pipeline Extension [Member] | OPSB [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost excluding AFUDC				245																															245					245				245
Duke Energy Ohio [Member] | MGP Cost Recovery - 2009 Through 2012 [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets				55																															55					55				55
Duke Energy Ohio [Member] | MGP Cost Recovery - 2013 Through 2017 [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																																																					$ 26
Duke Energy Ohio [Member] | MGP Cost Recovery - 2013 Through 2017 [Member] | PUCO [Member] | MGP Costs - Regulatory Disallowance [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																																																					$ 12
Duke Energy Ohio [Member] | MGP Cost Recovery - 2018 [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets				20																															20					20				20
Duke Energy Ohio [Member] | MGP Cost Recovery - 2018 [Member] | PUCO [Member] | MGP Costs - Regulatory Disallowance [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																																																$ 11
Duke Energy Kentucky [Member] | Duke Energy Kentucky Gas Base Rate Case [Member] | KPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount																			$ 11
Requested rate increase, percentage																			11.10%
Approved rate increase (decrease), amount															$ 7
Requested rate increase (decrease), amended amount																			$ (5)
Approved return on equity percentage															9.70%
Duke Energy Kentucky [Member] | Duke Energy Kentucky Electric Base Rate Case [Member] | KPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount						$ 46
Requested rate increase, percentage						12.50%
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								192		198		569	576
Loss before income taxes																																								(203)		(154)		(476)	(421)
Public utilities, property, plant and equipment, net				10,937																															10,937					10,937	10,529			$ 10,937
Impairment charges																																										30			30
Duke Energy Indiana [Member] | 2019 Indiana Rate Case [Member] | IURC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount					$ 395			$ 395
Requested rate increase, percentage								15.00%
Requested rate increase, percentage, net of tax								17.00%
Rate base																																									10,200
Requested rate increase (decrease), amended amount					393
Amount reduced from initial request					$ 2
Duke Energy Indiana [Member] | FERC Transmission Rates [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage																																												12.38%
Approved return on equity percentage adder																																	0.50%
Duke Energy Indiana [Member] | FERC Complaint [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Requested return on equity, percent																																												8.67%
Duke Energy Indiana [Member] | FERC Complaint 1 [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage																																10.32%
Duke Energy Indiana [Member] | FERC Complaint 2 [Member] | FERC [Member]
Public Utilities, General Disclosures [Line Items]
Requested return on equity, percent																															9.70%
Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																								78		85		$ 241	252
Loss before income taxes																																								28		$ 32		(119)	$ (102)
Public utilities, property, plant and equipment, net				$ 6,582																															$ 6,582					$ 6,582	$ 5,911			$ 6,582
Piedmont Natural Gas [Member] | North Carolina Integrity Management Rider Filing [Member] | TPUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease), amount										$ 9
Piedmont Natural Gas [Member] | Tennessee Integrity Management Rider Filing November 2018 [Member] | TPUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease), amount																																				$ 3
Piedmont Natural Gas [Member] | 2019 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount							$ 83						$ 83
Requested rate increase, percentage													9.00%
Requested rate increase (decrease), gross amount							$ 109
Requested return on equity, percent							9.70%
Public utilities, requested equity capital structure, percentage							52.00%
Public utilities, requested debt capital structure, percentage							48.00%
Change in tax rate, deferred tax liability, income tax benefit							$ 37
Measurement period adjustment, income tax expense (benefit)							23
Piedmont Natural Gas [Member] | 2019 North Carolina Rate Case [Member] | NCUC [Member] | Distribution Integrity Management Program [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets							11
Piedmont Natural Gas [Member] | State and Local Jurisdiction [Member] | North Carolina Department of Revenue [Member] | 2019 North Carolina Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
State and local taxes, increase (reduction), amount							$ (21)
Piedmont Natural Gas [Member] | Subsequent Event [Member] | North Carolina Integrity Management Rider Filing [Member] | TPUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	$ 11