Regulatory Matters (Narrative) (Details) (USD $)	12 Months Ended			36 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 31, 2017
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	$ 28,000,000	$ 64,000,000		$ 28,000,000
Net property, plant and equipment	70,046,000,000	69,490,000,000		70,046,000,000
Regulatory assets, current	1,115,000,000	895,000,000		1,115,000,000
Net Asset Percentage Limit	25.00%			25.00%
Payments to Acquire Businesses, Gross	54,000,000		451,000,000
Capitalized interest	75,000,000	89,000,000	176,000,000
Impairment charges	81,000,000	399,000,000	666,000,000
Regulatory assets, noncurrent	11,042,000,000	9,191,000,000		11,042,000,000
Regulatory liability, noncurrent	6,193,000,000	5,949,000,000		6,193,000,000
Regulatory assets	12,157,000,000	10,086,000,000		12,157,000,000
Capital expenditures	5,384,000,000	5,526,000,000	5,501,000,000
Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	1,659,000,000	1,748,000,000		1,659,000,000
Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	296,000,000	262,000,000		296,000,000
Atlantic Coast Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage	40.00%			40.00%
NCEMC [Member] | William States Lee Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage	13.00%			13.00%
Duke Energy Kentucky [Member]
Public Utilities, General Disclosures [Line Items]
Required Equity Capital Structure Percent	35.00%			35.00%
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	2,000,000	5,000,000		2,000,000
Net property, plant and equipment	24,672,000,000	23,012,000,000		24,672,000,000
Regulatory assets, current	399,000,000	295,000,000		399,000,000
Capitalized interest	38,000,000	41,000,000	72,000,000
Impairment charges	3,000,000		31,000,000
Regulatory assets, noncurrent	2,465,000,000	1,527,000,000		2,465,000,000
Regulatory liability, noncurrent	2,710,000,000	2,576,000,000		2,710,000,000
Regulatory assets	2,864,000,000	1,822,000,000		2,864,000,000
Capital expenditures	1,879,000,000	1,695,000,000	1,908,000,000
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	58,000,000	68,000,000		58,000,000
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	141,000,000	40,000,000		141,000,000
Duke Energy Carolinas [Member] | Minimum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period	5 years
Duke Energy Carolinas [Member] | Maximum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period	10 years
Duke Energy Carolinas [Member] | Rate Case Step One [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	204,000,000
Approved percentage rate increase by state commission	4.50%
Duke Energy Carolinas [Member] | Rate Case Step One [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	80,000,000
Approved percentage rate increase by state commission	5.50%
Duke Energy Carolinas [Member] | Rate Case Step Two [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	30,000,000
Approved percentage rate increase by state commission	0.60%
Duke Energy Carolinas [Member] | Rate Case Step Two [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	38,000,000
Approved percentage rate increase by state commission	2.60%
Duke Energy Carolinas [Member] | Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	10.20%
Approved equity capital structure, percentage	53.00%
Required shareholder contribution to low income customers or agencies.	10,000,000
Rate increase begin date	Sep. 25, 2013
Duke Energy Carolinas [Member] | Rate Case [Member] | NCUC [Member] | Removal Costs Reduction Year One [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability, noncurrent	30,000,000			30,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | NCUC [Member] | Removal Costs Reduction Year Two [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability, noncurrent	30,000,000			30,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	10.20%
Approved equity capital structure, percentage	53.00%
Required shareholder contribution to low income customers or agencies.	4,000,000
Rate increase begin date	Sep. 18, 2013
Duke Energy Carolinas [Member] | Rate Case [Member] | PSCSC [Member] | Removal Costs Reduction Year One [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability, noncurrent	45,000,000			45,000,000
Duke Energy Carolinas [Member] | William State Lee III Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	427,000,000			427,000,000
Duke Energy Carolinas [Member] | NCEMC [Member] | William States Lee Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	600,000,000			600,000,000
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	1,000,000	11,000,000		1,000,000
Net property, plant and equipment	15,186,000,000	13,650,000,000		15,186,000,000
Regulatory assets, current	287,000,000	127,000,000		287,000,000
Capitalized interest	10,000,000	16,000,000	23,000,000
Impairment charges	(18,000,000)	22,000,000	54,000,000
Regulatory assets, noncurrent	2,675,000,000	1,384,000,000		2,675,000,000
Regulatory liability, noncurrent	1,832,000,000	1,673,000,000		1,832,000,000
Regulatory assets	2,962,000,000	1,511,000,000		2,962,000,000
Capital expenditures	1,241,000,000	1,567,000,000	1,525,000,000
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period	10 years
Regulatory assets	152,000,000	241,000,000		152,000,000
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	43,000,000	77,000,000		43,000,000
Duke Energy Progress [Member] | Maximum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period	10 years
Duke Energy Progress [Member] | FERC Mitigation [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges	(18,000,000)
Duke Energy Progress [Member] | Rate Case Step One [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	147,000,000
Approved percentage rate increase by state commission	4.50%
Duke Energy Progress [Member] | Rate Case Step Two [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	31,000,000
Approved percentage rate increase by state commission	1.00%
Duke Energy Progress [Member] | Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	10.20%
Approved equity capital structure, percentage	53.00%
Required shareholder contribution to low income customers or agencies.	20,000,000
Rate increase begin date	Jun. 01, 2013
Duke Energy Progress [Member] | Rate Case [Member] | NCUC [Member] | Removal Costs Reduction Year One [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability, noncurrent	20,000,000			20,000,000
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges	22,000,000
Regulatory assets, noncurrent	48,000,000			48,000,000
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	17,000,000	24,000,000		17,000,000
Net property, plant and equipment	9,955,000,000	9,611,000,000		9,955,000,000
Regulatory assets, current	203,000,000	221,000,000		203,000,000
Capitalized interest	1,000,000	3,000,000	18,000,000
Impairment charges	2,000,000	358,000,000	146,000,000
Regulatory assets, noncurrent	2,733,000,000	2,729,000,000		2,733,000,000
Regulatory liability, noncurrent	547,000,000	618,000,000		547,000,000
Regulatory assets	2,936,000,000	2,950,000,000		2,936,000,000
Capital expenditures	699,000,000	915,000,000	809,000,000
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period	20 years
Regulatory assets	1,393,000,000	1,378,000,000		1,393,000,000
Duke Energy Florida [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	112,000,000	145,000,000		112,000,000
Duke Energy Florida [Member] | FPSC [Member] | Removal Costs [Member]
Public Utilities, General Disclosures [Line Items]
Amount of reduction to carrying amount of regulatory liabilities		114,000,000	178,000,000
Duke Energy Florida [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	10.80%
Duke Energy Florida [Member] | FERC Complaint 1 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	9.02%
Duke Energy Florida [Member] | FERC Complaint 2 [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	8.63%
Duke Energy Florida [Member] | FERC Complaint 2 [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	8.84%
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] | 2013 FPSC Settlement Agreement [Member] | New Generation Needs [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	10.50%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	9.50%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	11.50%
Duke Energy Florida [Member] | 2012 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, current	50,000,000			50,000,000
Approved rate increase amount by state commission	150,000,000
Customer Refund Liability, Current	120,000,000			120,000,000
Total Customer Refunds To Be Paid	388,000,000
Regulatory liability, noncurrent	70,000,000			70,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Public Utilities, General Disclosures [Line Items]
Decommissioning cost study estimate	1,180,000,000			1,180,000,000
Regulatory assets, current	295,000,000			295,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Acceleration of cash recovery through fuel clause	130,000,000
Cost Cap for customers	1,466,000,000			1,466,000,000
Approved return on equity percentage amount by state commission	7.35%
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | Amount Subject To Cost Cap [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	1,377,000,000			1,377,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | Uprate And ISFSI Projects [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	260,000,000			260,000,000
Duke Energy Florida [Member] | Levy Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	25,000,000			25,000,000
Duke Energy Florida [Member] | Levy Nuclear Station [Member] | 2013 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Net unrecovered investment	180,000,000			180,000,000
Net property, plant and equipment	91,000,000			91,000,000
Regulatory assets, current	89,000,000			89,000,000
Impairment charges	65,000,000
Duke Energy Florida [Member] | Citrus County Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	1,500,000,000			1,500,000,000
Duke Energy Florida [Member] | Suwannee Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	197,000,000			197,000,000
Duke Energy Florida [Member] | Hines Energy Complex [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	160,000,000			160,000,000
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	6,000,000	2,000,000		6,000,000
Net property, plant and equipment	4,937,000,000	8,235,000,000		4,937,000,000
Regulatory assets, current	49,000,000	57,000,000		49,000,000
Limit of Total Capital	30.00%			30.00%
Capitalized interest	10,000,000	11,000,000	13,000,000
Impairment charges	94,000,000	5,000,000	2,000,000
Approved MVP Proposals	17
MISO estimate of Duke Energy Ohio's MVP obligation	2,700,000,000
Regulatory assets, noncurrent	512,000,000	471,000,000		512,000,000
Regulatory liability, noncurrent	241,000,000	262,000,000		241,000,000
Regulatory assets	561,000,000	528,000,000		561,000,000
Capital expenditures	322,000,000	434,000,000	514,000,000
Duke Energy Ohio [Member] | Capacity Rider Filing [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase amount to state commission	729,000,000
Duke Energy Ohio [Member] | Electric Rate Case [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	49,000,000
Approved percentage rate increase by state commission	2.90%
Approved return on equity percentage amount by state commission	9.84%
Rate increase begin date	May 01, 2013
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] | Mgp Remediation [Member]
Public Utilities, General Disclosures [Line Items]
Required Bond Amount	2,500,000			2,500,000
Duke Energy Ohio [Member] | Mgp Remediation [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase amount by state commission	56,000,000
Regulatory assets	115,000,000			115,000,000
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] | 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] | W.C. Beckjord Station [Member]
Public Utilities, General Disclosures [Line Items]
Gallons of Fuel Released	9,000			9,000
Duke Energy Ohio [Member] | RTO Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve	94,000,000	95,000,000		94,000,000
Regulatory assets	74,000,000			74,000,000
Duke Energy Ohio [Member] | Dayton Power and Light [Member] | East Bend Station [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage	31.00%			31.00%
Capital expenditures	12,400,000
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	8,815,000,000	8,576,000,000		8,815,000,000
Regulatory assets, current	93,000,000	118,000,000		93,000,000
Capitalized interest	6,000,000	9,000,000	39,000,000
Impairment charges	0	0	579,000,000
Regulatory assets, noncurrent	685,000,000	717,000,000		685,000,000
Regulatory liability, noncurrent	796,000,000	782,000,000		796,000,000
Regulatory assets	778,000,000	835,000,000		778,000,000
Capital expenditures	625,000,000	545,000,000	718,000,000
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets	56,000,000	61,000,000		56,000,000
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 1 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission	9.15%
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	1,900,000,000			1,900,000,000
Percentage Recovered Through Rider	80.00%
Percentage Recovered Through Future Rate Case	20.00%
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member]
Public Utilities, General Disclosures [Line Items]
Percent of AFUDC Allowed	85.00%
Impairment charges			631,000,000	897,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member] | Edwardsport Event November 20, 2007 [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	1,985,000,000			1,985,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member] | Edwardsport Event December 27, 2012 [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC	2,595,000,000			2,595,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member] | Edwardsport Event September 8, 2014 [Member]
Public Utilities, General Disclosures [Line Items]
Capitalized interest	61,000,000
Dominion Resources [Member] | Atlantic Coast Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage	45.00%			45.00%
Scenario, Forecast [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Payments to Acquire Businesses, Gross					$ 166,000,000