Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 31, 2015 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) MW	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		$ 84,404.0		$ 84,404.0		$ 82,520.0
Generation Facilities To Be Retired Net		487.0		487.0		529.0
Electric Domestic Regulated Revenue		5,118.0	$ 4,965.0	$ 10,031.0	$ 10,018.0
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW				1,738
Public Utilities, Property, Plant and Equipment, Net		$ 416.0		$ 416.0
Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		47.00%		47.00%
Long-term Purchase Commitment, Period				20 years
Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		7.50%		7.50%
Estimated capital cost		$ 3,200.0		$ 3,200.0
Long-term Purchase Commitment, Period				25 years
Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		24.00%		24.00%
Estimated Contributions		$ 229.0		$ 229.0
Minimum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		5,000.0		5,000.0
Maximum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		$ 5,500.0		$ 5,500.0
Dominion Resources [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		48.00%		48.00%
Southern Company Gas [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		5.00%		5.00%
Spectra Energy [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		50.00%		50.00%
NextEra [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		42.50%		42.50%
Williams Partners L.P. [Member] | Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		41.00%		41.00%
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		$ 27,249.0		$ 27,249.0		26,762.0
Duke Energy Carolinas [Member] | William States Lee Combined Cycle Facility [Member] | NCEMC [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		$ 600.0		$ 600.0
Joint owner ownership percentage		13.00%		13.00%
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		$ 31,152.0		$ 31,152.0		30,181.0
Generation Facilities To Be Retired Net		487.0		487.0		529.0
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		18,689.0		18,689.0		18,387.0
Generation Facilities To Be Retired Net		487.0		$ 487.0		529.0
Duke Energy Progress [Member] | Asheville Plant [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW				376
Generation Facilities To Be Retired Net		450.0		$ 450.0		492.0
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		12,459.0		12,459.0		11,790.0
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		5,722.0		5,722.0		5,547.0
Electric Domestic Regulated Revenue		328.0	$ 323.0	665.0	$ 663.0
Duke Energy Ohio [Member] | Regional Transmission Organization Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Exit obligation		90.0		90.0		90.0
Regulatory Assets		$ 71.0		$ 71.0		71.0
Approved MVP Proposals		17		17
MISO estimate of Duke Energy Ohio's MVP obligation				$ 2,700.0
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		$ 10,089.0		10,089.0		9,924.0
Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net		5,006.0		5,006.0		$ 4,814.0
2017 Base Rate Case [Member] | NCUC [Member] | Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount				$ 477.0
Requested Rate Increase, Percentage				14.90%
2017 Base Rate Case [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount				$ 15.0
Requested Return on Equity, Percentage				10.40%
Storm Cost Deferrals [Member] | NCUC [Member] | Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved		116.0		$ 116.0
Western Carolinas Modernization Plan [Member] | NCUC [Member] | Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		893.0		893.0
Hines Chiller Uprate Project [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		150.0		150.0
Hines Chiller Uprate Project [Member] | FPSC [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount				19.0
Levy Nuclear Project [Member] | FPSC [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount				82.0
Woodsdale Station Fuel System [Member] | KPSC [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		55.0		55.0
East Bend Coal Ash Basin Filing [Member] | KPSC [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		93.0		93.0
Natural Gas Pipeline Extension [Member] | PUCO [Member] | Duke Energy Ohio [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC		86.0		86.0
Natural Gas Pipeline Extension [Member] | PUCO [Member] | Duke Energy Ohio [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC		110.0		110.0
Advanced Metering Infrastructure Project [Member] | KPSC [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved		10.0		10.0
Estimated capital cost		49.0		49.0
Accelerated Natural Gas Service Line Replacement Rider [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved		240.0		240.0
Energy Efficiency and Peak Demand Reduction Program [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Electric Domestic Regulated Revenue	$ 20.0
MGP Remediation [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets		$ 95.0		95.0
Coal Combustion Residual Plan [Member] | IURC [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount				365.0
Requested Rate Increase (Decrease), Amount				$ 380.0
Federal Mandate Costs Recovered Through Tracker Mechanism				80.00%
Federally Mandated Costs Recovered In Future Rate Case				20.00%
Percentage of Costs Recovered through Existing Rider				60.00%
Percentage Recovered Through Future Rate Case				40.00%
Interest Rate on Intermediary Debt for Electric Utility Plant Construction				4.73%
FERC Transmission Rates [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage				12.38%
Approved Return on Equity Percentage Adder				0.50%
FERC Complaint [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage				8.67%
FERC Complaint 1 [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage				10.32%
FERC Complaint 2 [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage				9.70%
NCUC IMR Petition Filed May 2017 [Member] | NCUC [Member] | Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount				$ 11.6