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Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended
Regulatory Matters (Narrative) (Details) $ in Millions	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($) MW	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	$ 11,373.0		$ 11,483.0
Electric Domestic Regulated Revenue			5,053.0		$ 5,457.0
Payments to Acquire Businesses, Gross					29.0
Property, Plant and Equipment, Net	75,709.0		$ 76,432.0
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) \| MW			1,471
Property, Plant and Equipment, Net			$ 300.0
Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			40.00%
Atlantic Coast Pipeline (ACP) [Member] \| Dominion Resources [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			45.00%
Atlantic Coast Pipeline (ACP) [Member] \| Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			10.00%
Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			7.50%
Sabal Trail Transmission Pipeline [Member] \| Spectra Energy [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			59.50%
Sabal Trail Transmission Pipeline [Member] \| NextEra [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			33.00%
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	2,766.0		$ 2,801.0
Property, Plant and Equipment, Net	25,877.0		$ 26,064.0
Duke Energy Carolinas [Member] \| FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission			10.20%
Duke Energy Carolinas [Member] \| FERC Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage			8.49%
Duke Energy Carolinas [Member] \| William States Lee Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC			$ 600.0
Duke Energy Carolinas [Member] \| William States Lee Combined Cycle Facility [Member] \| NCEMC [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			13.00%
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	5,435.0		$ 5,498.0
Property, Plant and Equipment, Net	28,347.0		$ 28,689.0
Progress Energy [Member] \| Crystal River Units 1 and 2 [Member] \| Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) \| MW			873
Property, Plant and Equipment, Net			$ 128.0
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	2,710.0		2,768.0
Property, Plant and Equipment, Net	17,720.0		17,768.0
Duke Energy Progress [Member] \| Western Carolinas Modernization Plan [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			$ 1,100.0
Duke Energy Progress [Member] \| FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission			10.80%
Duke Energy Progress [Member] \| FERC Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage			8.49%
Duke Energy Progress [Member] \| Asheville Plant [Member] \| Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) \| MW			376
Property, Plant and Equipment, Net	548.0		$ 531.0
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	2,725.0		2,730.0
Property, Plant and Equipment, Net	10,623.0		$ 10,918.0
Duke Energy Florida [Member] \| Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Payments to Acquire Businesses, Gross		$ 166.0
Duke Energy Florida [Member] \| Crystal River Units 1 and 2 [Member] \| Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) \| MW			873
Property, Plant and Equipment, Net			$ 128.0
Duke Energy Florida [Member] \| Crystal River Unit 3 [Member] \| 2013 FPSC Settlement Agreement[Member] \| FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved	1,298.0
Regulatory assets, noncurrent	1,283.0
Public Utilities, Approved Rate Increase (Decrease), Amount			(36.0)
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	497.0		503.0
Electric Domestic Regulated Revenue			340.0		$ 339.0
Property, Plant and Equipment, Net	5,243.0		5,288.0
Duke Energy Ohio [Member] \| Accelerated Natural Gas Service Line Replacement Rider [Member] \| PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital and operations and maintenance cost			320.0
Duke Energy Ohio [Member] \| Energy Efficiency and Peak Demand Reduction Program [Member] \| PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Electric Domestic Regulated Revenue	20.0
Duke Energy Ohio [Member] \| Regional Transmission Organization [Member]
Public Utilities, General Disclosures [Line Items]
Exit obligation	92.0		91.0
Regulatory assets, noncurrent			$ 72.0
Duke Energy Ohio [Member] \| RTO Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Approved MVP Proposals			17
MISO estimate of Duke Energy Ohio's MVP obligation			$ 2,700.0
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	716.0		766.0
Property, Plant and Equipment, Net	$ 9,523.0		$ 9,505.0
Duke Energy Indiana [Member] \| Coal Combustion Residual Plan [Member]
Public Utilities, General Disclosures [Line Items]
Federal Mandate Costs Recovered Through Tracker Mechanism			80.00%
Federally Mandated Costs Recovered In Future Rate Case			20.00%
Duke Energy Indiana [Member] \| FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission			12.38%
Duke Energy Indiana [Member] \| FERC Transmission Rates [Member] \| Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission			0.50%
Duke Energy Indiana [Member] \| FERC Complaint 2 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage			8.67%
Duke Energy Indiana [Member] \| FERC Complaint 2 [Member] \| Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage			10.32%
Duke Energy Indiana [Member] \| Grid Infrastructure Improvement Plan [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			$ 1,900.0
Duke Energy Indiana [Member] \| Revised Grid Infrastructure Improvement Plan [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage			10.00%
Estimated capital cost			$ 1,800.0
Public Utilities, Requested Rate Increase (Decrease), Amount			1,400.0
Duke Energy Indiana [Member] \| Edwardsport Igcc Plant [Member] \| IGCC Rider Proceeding [Member] \| IURC [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			87.5
Legal Fees			$ 5.5
Utilities Operating Expense, Other				$ 93.0
Regulatory Asset, Amortization Period			8 years
Regulatory Assets			$ 147.0