Regulatory Matters (Narrative) (Details) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($)	Jun. 30, 2015 USD ($) MW	Jun. 30, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		$ 11,564.0			$ 11,042.0
Payments to Acquire Businesses, Gross		$ 29.0	$ 16.0
Capacity (in MW) | MW		1,541
Property, Plant and Equipment, Net		$ 71,759.0			70,046.0
Payments to Acquire Property, Plant, and Equipment		$ 3,062.0	2,400.0
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%
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%
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		$ 237.0
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		2,631.0			2,465.0
Property, Plant and Equipment, Net		24,965.0			24,672.0
Payments to Acquire Property, Plant, and Equipment		954.0	851.0
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%
Duke Energy Carolinas [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		$ 110.0
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		3,119.0			2,675.0
Property, Plant and Equipment, Net		15,571.0			15,186.0
Payments to Acquire Property, Plant, and Equipment		699.0	540.0
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] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW		376
Property, Plant and Equipment, Net		$ 460.0
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		$ 2,694.0			2,733.0
Capacity (in MW) | MW		873
Property, Plant and Equipment, Net		$ 10,229.0			9,955.0
Payments to Acquire Property, Plant, and Equipment		$ 471.0	348.0
Duke Energy Florida [Member] | Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Payments to Acquire Businesses, Gross	$ 166.0
Duke Energy Florida [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage		10.00%
Approved return on equity percentage amount by state commission		10.80%
Customer Refund Liability, Noncurrent		$ 14.1
Duke Energy Florida [Member] | FERC Complaint 3 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission		8.69%
Duke Energy Florida [Member] | Citrus County Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		$ 1,500.0
Duke Energy Florida [Member] | Suwannee Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		197.0
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement[Member] | FPSC [Member] | Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent				$ 1,298.0
Public Utilities, Requested Rate Increase (Decrease), Amount				170.0
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | Crystal River Unit 3 Requested Financing Order [Member] | FPSC [Member] | Scenario, Forecast [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 100.0
Duke Energy Florida [Member] | Levy Nuclear Station [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		54.0
Duke Energy Florida [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		125.0
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		506.0			512.0
Property, Plant and Equipment, Net		5,117.0			4,937.0
Payments to Acquire Property, Plant, and Equipment		$ 166.0	167.0
Duke Energy Ohio [Member] | FERC Complaint 1 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission		11.38%
Duke Energy Ohio [Member] | MGP Remediation [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission		$ 56.0
Duke Energy Ohio [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission		12.38%
Percentage Recovered Through Future Rate Case		30.00%
Duke Energy Ohio [Member] | Natural Gas Rate Case [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission		9.84%
Duke Energy Ohio [Member] | RTO Realignment [Member]
Public Utilities, General Disclosures [Line Items]
MISO estimate of Duke Energy Ohio's MVP obligation		$ 2,700.0
Duke Energy Ohio [Member] | East Bend Station [Member] | Dayton Power and Light [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		31.00%
Payments to Acquire Property, Plant, and Equipment		$ 12.4
Duke Energy Ohio [Member] | Regional Transmission Organization [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		73.0
Restructuring Reserve		93.0
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		$ 707.0			685.0
Capacity (in MW) | MW		668
Property, Plant and Equipment, Net		$ 9,323.0			$ 8,815.0
Payments to Acquire Property, Plant, and Equipment		$ 380.0	$ 291.0
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%
Percentage Recovered Through Future Rate Case		0.50%
Duke Energy Indiana [Member] | FERC Complaint 2 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission		8.67%
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] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net		$ 112.0