Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

Defined Benefit Plan Disclosure [Line Items]

Pension Plan Contributions

Duke Energy’s policy is to fund amounts on an actuarial basis to provide assets sufficient to meet benefit payments to be paid to plan participants. The following table includes information related to the Duke Energy Registrants’ contributions to its U.S. qualified defined benefit pension plans.

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Anticipated Contributions:
2016	$	145	$	43	$	43	$	24	$	20	$	4	$	9
Contributions Made:
2015	$	302	$	91	$	83	$	42	$	40	$	8	$	19
2014	—		—		—		—		—		—		—
2013	250		—		250		63		133		—		—

Employee Savings Plan Matching Contributions

The following table includes pretax employer matching contributions made by Duke Energy and expensed by the Subsidiary Registrants.

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Years ended December 31,
2015(a)	$	159	$	54	$	48	$	34	$	13	$	3	$	7
2014(a)	143		47		43		30		14		3		7
2013	134		45		45		25		14		3		7

(a) For 2014 and 2015, amounts include the additional employer contribution of 4 percent of eligible pay per pay period for employees not eligible to participate in a defined benefit plan.

Master Trust [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value and Allocation of Plan Assets

The following tables provide the fair value measurement amounts for the Duke Energy Master Retirement Trust qualified pension and other post-retirement assets.

	December 31, 2015
	Total Fair										Not
(in millions)	Value			Level 1			Level 2		Level 3		Categorized(b)
Equity securities	$	2,160		$	1,470		$	2	$	—	688
Corporate debt securities	4,362			—			4,362		—		—
Short-term investment funds	404			192			212		—		—
Partnership interests	185			—			—		—		185
Hedge funds	210			—			—		—		210
Real estate limited partnerships	118			—			—		—		118
U.S. government securities	748			—			748		—		—
Guaranteed investment contracts	31			—			—		31		—
Governments bonds – foreign	34			—			34		—		—
Cash	10			10			—		—		—
Government and commercial mortgage backed securities	9			—			9		—		—
Net pending transactions and other investments	(28		)	(36		)	8		—		—
Total assets(a)	$	8,243		$	1,636		$	5,375	$	31	$	1,201

(a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 28 percent, 32 percent, 15 percent, 16 percent, 5 percent and 8 percent, respectively, of the Duke Energy Master Retirement Trust assets at December 31, 2015. Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages.

(b) Certain investments are not categorized. These investments are measured based on the fair value of the underlying investments but may not be readily redeemable at that fair value.

	December 31, 2014
	Total Fair									Not
(in millions)	Value		Level 1			Level 2		Level 3		Categorized(b)
Equity securities	$	2,346	$	1,625		$	3	$	—	$	718
Corporate debt securities	4,349		—			4,348		1		—
Short-term investment funds	333		171			162		—		—
Partnership interests	298		—			—		—		298
Hedge funds	146		—			—		—		146
Real estate limited partnerships	104		—			—		—		104
U.S. government securities	917		—			916		1		—
Guaranteed investment contracts	32		—			—		32		—
Governments bonds – foreign	44		—			44		—		—
Cash	30		30			—		—		—
Government and commercial mortgage backed securities	9		—			9		—		—
Net pending transactions and other investments	10		(10		)	20		—		—
Total assets(a)	$	8,618	$	1,816		$	5,502	$	34	$	1,266

(a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 28 percent, 31 percent, 15 percent, 16 percent, 5 percent and 8 percent, respectively, of the Duke Energy Master Retirement Trust assets at December 31, 2014. Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages.

(b) Certain investments are not categorized. These investments are measured based on the fair value of the underlying investments but may not be readily redeemable at that fair value.

The following table includes the target asset allocations by asset class at December 31, 2015 and the actual asset allocations for the Duke Energy Master Retirement Trust.

			Actual Allocation at
			December 31,
	Target
	Allocation		2015		2014
U.S. equity securities	10	%	11	%	10	%
Non-U.S. equity securities	8	%	8	%	8	%
Global equity securities	10	%	10	%	10	%
Global private equity securities	3	%	2	%	3	%
Debt securities	63	%	63	%	63	%
Hedge funds	2	%	2	%	3	%
Real estate and cash	2	%	2	%	1	%
Other global securities	2	%	2	%	2	%
Total	100	%	100	%	100	%

Master Trust Level 3 Rollforward

The following table provides a reconciliation of beginning and ending balances of assets of master trusts measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3).

(in millions)	2015			2014
Balance at January 1	$	34		$	37
Sales	(2		)	(4		)
Total gains (losses) and other, net	(1		)	1
Balance at December 31	$	31		$	34

Voluntary Employee Beneficiary Association [Member]

Defined Benefit Plan Disclosure [Line Items]

Fair Value and Allocation of Plan Assets

The following table presents target and actual asset allocations for VEBA I at December 31, 2015.

			Actual Allocation at
	Target		December 31,
	Allocation		2015		2014
U.S. equity securities	30	%	29	%	29	%
Debt securities	45	%	28	%	28	%
Cash	25	%	43	%	43	%
Total	100	%	100	%	100	%

The following tables provide the fair value measurement amounts for VEBA I other post-retirement assets.

	December 31, 2015
	Total Fair
(in millions)	Value		Level 1	Level 2		Level 3
Cash and cash equivalents	$	18	—	$	18	—
Equity securities	12		—	12		—
Debt securities	12		—	12		—
Total assets	$	42	—	$	42	—

	December 31, 2014
	Total Fair
(in millions)	Value		Level 1	Level 2		Level 3
Cash and cash equivalents	$	21	—	$	21	—
Equity securities	14		—	14		—
Debt securities	13		—	13		—
Total assets	$	48	—	$	48	—

Qualified Pension Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

Components of Net Periodic Pension Costs

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	159		$	50		$	44		$	23		$	20		$	4		$	10
Interest cost on projected benefit obligation	324			83			104			48			54			18			27
Expected return on plan assets	(516		)	(139		)	(171		)	(79		)	(87		)	(26		)	(42		)
Amortization of actuarial loss	166			39			65			33			31			7			13
Amortization of prior service (credit) cost	(15		)	(7		)	(3		)	(2		)	(1		)	—			1
Other	8			2			3			1			1			—			1
Net periodic pension costs(a)(b)	$	126		$	28		$	42		$	24		$	18		$	3		$	10

	Year Ended December 31, 2014
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	135		$	41		$	40		$	21		$	20		$	4		$	9
Interest cost on projected benefit obligation	344			85			112			54			57			20			29
Expected return on plan assets	(511		)	(132		)	(173		)	(85		)	(85		)	(27		)	(41		)
Amortization of actuarial loss	150			36			68			32			32			4			13
Amortization of prior service credit	(15		)	(8		)	(3		)	(2		)	(1		)	—			—
Other	8			2			3			1			1			—			1
Net periodic pension costs(a)(b)	$	111		$	24		$	47		$	21		$	24		$	1		$	11

	Year Ended December 31, 2013
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	167		$	49		$	60		$	22		$	30		$	6		$	11
Interest cost on projected benefit obligation	320			80			116			50			53			21			28
Expected return on plan assets	(549		)	(148		)	(199		)	(94		)	(87		)	(31		)	(46		)
Amortization of actuarial loss	244			60			101			46			49			13			24
Amortization of prior service (credit) cost	(11		)	(6		)	(4		)	(1		)	(2		)	—			1
Other	7			2			2			1			1			—			1
Net periodic pension costs(a)(b)	$	178		$	37		$	76		$	24		$	44		$	9		$	19

(a) Duke Energy amounts exclude $9 million, $10 million, and $12 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

(b) Duke Energy Ohio amounts exclude $4 million, $5 million, and $6 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

Amounts Recognized in AOCI and Regulatory Assets and Liabilities

Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets

	Year Ended December 31, 2015
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Regulatory assets, net increase	$	173		$	65	$	18		$	14	$	4	$	14	$	11
Accumulated other comprehensive loss (income)
Deferred income tax expense	$	6		—		5			—		—		—		—
Actuarial losses arising during the year	4			—		—			—		—		—		—
Amortization of prior year service credit	1			—		—			—		—		—		—
Amortization of prior year actuarial losses	(11		)	—		(4		)	—		—		—		—
Transfer with the disposal group	3
Reclassification of actuarial losses to regulatory assets	(6		)	—		—			—		—		—		—
Net amount recognized in accumulated other comprehensive income	$	(3	)	$	—	$	1		$	—	$	—	$	—	$	—

	Year Ended December 31, 2014
				Duke					Duke			Duke		Duke		Duke
	Duke			Energy		Progress			Energy			Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress			Florida		Ohio		Indiana
Regulatory assets, net increase (decrease)	$	112		$	30	$	(73	)	$	(17	)	$	11	$	17	$	4
Accumulated other comprehensive (income) loss
Deferred income tax expense	$	(10	)	$	—	$	(2	)	$	—		$	—	$	—	$	—
Actuarial losses arising during the year	29			—		—			—			—		—		—
Prior year service credit arising during the year	—			—		—			—			—		—		—
Amortization of prior year actuarial losses	(9		)	—		—			—			—		—		—
Reclassification of actuarial losses to regulatory assets	(1		)	—		—			—			—		—		—
Net amount recognized in accumulated other comprehensive income	$	9		$	—	$	(2	)	$	—		$	—	$	—	$	—

Reconciliation of Funded Status to Net Amount Recognized

Reconciliation of Funded Status to Net Amount Recognized

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	8,107		$	2,053		$	2,557		$	1,187		$	1,335		$	469		$	673
Obligation transferred with the Disposal Group	(83		)	—			—			—			—			—			—
Service cost	159			50			44			23			20			4			10
Interest cost	324			83			104			48			54			18			27
Actuarial gain	(241		)	(53		)	(111		)	(46		)	(62		)	(9		)	(15		)
Transfers	—			8			4			7			(3		)	8			—
Plan amendments	(6		)	—			—			—			—			—			(4		)
Benefits paid	(533		)	(146		)	(147		)	(76		)	(68		)	(37		)	(42		)
Obligation at measurement date	$	7,727		$	1,995		$	2,451		$	1,143		$	1,276		$	453		$	649
Accumulated Benefit Obligation at measurement date	$	7,606		$	1,993		$	2,414		$	1,143		$	1,240		$	442		$	628
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	8,498		$	2,300		$	2,722		$	1,321		$	1,363		$	456		$	681
Plan assets transferred with the Disposal Group	(81		)	—			—			—			—			—			—
Employer contributions	302			91			83			42			40			8			19
Actual return on plan assets	(50		)	(10		)	(22		)	(10		)	(11		)	(2		)	(3		)
Benefits paid	(533		)	(146		)	(147		)	(76		)	(68		)	(37		)	(42		)
Transfers	—			8			4			7			(3		)	8			—
Plan assets at measurement date	$	8,136		$	2,243		$	2,640		$	1,284		$	1,321		$	433		$	655
Funded status of plan	$	409		$	248		$	189		$	141		$	45		$	(20	)	$	6

	Year Ended December 31, 2014
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	7,510		$	1,875		$	2,739		$	1,172		$	1,233		$	442		$	632
Service cost	135			41			40			21			20			4			9
Interest cost	344			85			112			54			57			20			29
Actuarial loss(a)	618			132			211			98			105			41			41
Transfers	—			37			(375		)	(61		)	(9		)	(6		)	—
Plan amendments	(4		)	(1		)	—			—			—			(1		)	—
Benefits paid	(496		)	(116		)	(170		)	(97		)	(71		)	(31		)	(38		)
Obligation at measurement date	$	8,107		$	2,053		$	2,557		$	1,187		$	1,335		$	469		$	673
Accumulated Benefit Obligation at measurement date	$	7,966		$	2,052		$	2,519		$	1,187		$	1,297		$	459		$	645
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	8,142		$	2,162		$	2,944		$	1,330		$	1,299		$	448		$	654
Actual return on plan assets	852			217			300			149			144			45			65
Benefits paid	(496		)	(116		)	(170		)	(97		)	(71		)	(31		)	(38		)
Transfers	—			37			(352		)	(61		)	(9		)	(6		)	—
Plan assets at measurement date	$	8,498		$	2,300		$	2,722		$	1,321		$	1,363		$	456		$	681
Funded status of plan	$	391		$	247		$	165		$	134		$	28		$	(13	)	$	8

(a) Includes an increase in benefit obligation of $180 million as a result of changes in Duke Energy's mortality assumptions.

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Prefunded pension(a)	$	474		$	252		$	232		$	145		$	84		$	1		$	6
Noncurrent pension liability(b)	$	65		$	4		$	43		$	4		$	39		$	21		$	—
Net asset recognized	$	409		$	248		$	189		$	141		$	45		$	(20	)	$	6
Regulatory assets	$	1,884		$	472		$	771		$	360		$	410		$	79		$	162
Accumulated other comprehensive (income) loss
Deferred income tax asset	$	(45	)	$	—		$	(6	)	$	—		$	—		$	—		$	—
Prior service credit	(4		)	—			—			—			—			—			—
Net actuarial loss	130			—			17			—			—			—			—
Net amounts recognized in accumulated other comprehensive loss(c)	$	81		$	—		$	11		$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension costs in the next year
Unrecognized net actuarial loss	$	132		$	31		$	59		$	25		$	31		$	4		$	11
Unrecognized prior service credit	(16		)	(8		)	(3		)	(2		)	(1		)	—			—

	December 31, 2014
				Duke					Duke		Duke		Duke			Duke
	Duke			Energy		Progress			Energy		Energy		Energy			Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio			Indiana
Prefunded pension(a)	$	441		$	247	$	165		$	134	$	28	$	—		$	8
Noncurrent pension liability(b)	$	50		$	—	$	—		$	—	$	—	$	13		$	—
Net asset recognized	$	391		$	247	$	165		$	134	$	28	$	(13	)	$	8
Regulatory assets	$	1,711		$	407	$	753		$	346	$	406	$	65		$	151
Accumulated other comprehensive (income) loss
Deferred income tax asset	$	(51	)	$	—	$	(11	)	$	—	$	—	$	—		$	—
Prior service credit	(5		)	—		—			—		—		—			—
Net actuarial loss	140			—		21			—		—		—			—
Net amounts recognized in accumulated other comprehensive loss(c)	$	84		$	—	$	10		$	—	$	—	$	—		$	—

(a) Included in Other within Investments and Other Assets on the Consolidated Balance Sheets.

(b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.

(c) Excludes accumulated other comprehensive income of $13 million and $22 million as of December 31, 2015 and 2014, respectively, net of tax, associated with a Brazilian retirement plan.

Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets

	December 31, 2014
			Duke
	Duke		Energy
(in millions)	Energy		Ohio
Projected benefit obligation	$	702	$	315
Accumulated benefit obligation	672		306
Fair value of plan assets	652		302

Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets

	December 31, 2015
					Duke		Duke
	Duke		Progress		Energy		Energy
(in millions)	Energy		Energy		Florida		Ohio
Projected benefit obligation	$	1,216	$	611	$	611	$	307
Accumulated benefit obligation	1,158		575		575		298
Fair value of plan assets	1,151		574		574		289

Assumptions Used for Pension Benefits Accounting

The following tables present the assumptions or range of assumptions used for pension benefit accounting.

	December 31,
	2015				2014				2013
Benefit Obligations
Discount rate				4.40%				4.10%				4.70%
Salary increase	4.00	%	-	4.40%	4.00	%	-	4.40%	4.00	%	-	4.40%
Net Periodic Benefit Cost
Discount rate				4.10%				4.70%				4.10%
Salary increase	4.00	%	-	4.40%	4.00	%	-	4.40%	4.00	%	-	4.30%
Expected long-term rate of return on plan assets				6.50%				6.75%				7.75%

Expected Benefit Payments

Expected Benefit Payments

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Years ending December 31,
2016	$	628	$	189	$	164	$	91	$	71	$	35	$	48
2017	639		199		167		92		73		35		47
2018	640		203		169		92		75		34		47
2019	643		202		171		91		77		34		47
2020	641		201		174		92		80		35		47
2021 – 2025	3,053		906		869		438		420		171		230

Non-Qualified Pension Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

Components of Net Periodic Pension Costs

	Year Ended December 31, 2015
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Service cost	$	3		$	—	$	1		$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	13			1		4			1		2		—		—
Amortization of actuarial loss	6			—		2			1		2		—		1
Amortization of prior service credit	(1		)	—		(1		)	—		—		—		—
Net periodic pension costs	$	21		$	1	$	6		$	2	$	4	$	—	$	1

	Year Ended December 31, 2014
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Service cost	$	3		$	—	$	1		$	1	$	—	$	—	$	—
Interest cost on projected benefit obligation	14			1		5			1		2		—		—
Amortization of actuarial loss	3			—		2			—		—		—		—
Amortization of prior service credit	(1		)	—		(1		)	—		—		—		—
Net periodic pension costs	$	19		$	1	$	7		$	2	$	2	$	—	$	—

	Year Ended December 31, 2013
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Service cost	$	3		$	—	$	1		$	1	$	—	$	—	$	—
Interest cost on projected benefit obligation	13			1		7			1		1		—		—
Amortization of actuarial loss	5			—		3			1		1		—		—
Amortization of prior service credit	(1		)	—		(1		)	—		—		—		—
Net periodic pension costs	$	20		$	1	$	10		$	3	$	2	$	—	$	—

Amounts Recognized in AOCI and Regulatory Assets and Liabilities

Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities

	Year Ended December 31, 2015
				Duke					Duke			Duke			Duke		Duke
	Duke			Energy		Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress			Florida			Ohio		Indiana
Regulatory assets, net (decrease) increase	$	(13	)	$	2	$	(16	)	$	(1	)	$	(15	)	$	—	$	(1	)
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(7	)	$	—	$	(5	)	$	—		$	—		$	—	$	—
Amortization of prior service credit	1			—		—			—			—			—		—
Actuarial gains arising during the year	17			—		13			—			—			—		—
Net amount recognized in accumulated other comprehensive loss (income)	$	11		$	—	$	8		$	—		$	—		$	—	$	—

	Year Ended December 31, 2014
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Regulatory assets, net increase	$	44		$	1	$	14		$	4	$	19	$	1	$	2
Regulatory liabilities, net decrease	$	(7	)	$	—	$	—		$	—	$	—	$	—	$	—
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	4		$	—	$	5		$	—	$	—	$	—	$	—
Actuarial gains arising during the year	(9		)	—		(11		)	—		—		—		—
Net amount recognized in accumulated other comprehensive loss (income)	$	(5	)	$	—	$	(6	)	$	—	$	—	$	—	$	—

Reconciliation of Funded Status to Net Amount Recognized

Reconciliation of Funded Status to Net Amount Recognized

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	337		$	16		$	116		$	35		$	61		$	4	$	5
Service cost	3			—			1			—			—			—		—
Interest cost	13			1			4			1			2			—		—
Actuarial losses (gains)	10			1			(1		)	—			(14		)	—		—
Transfers	4			—			—			—			—			—		—
Benefits paid	(26		)	(2		)	(8		)	(3		)	(3		)	—		—
Obligation at measurement date	$	341		$	16		$	112		$	33		$	46		$	4	$	5
Accumulated Benefit Obligation at measurement date	$	336		$	16		$	112		$	33		$	46		$	4	$	5
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	—			—			—			—			—			—		—
Benefits paid	(26		)	(2		)	(8		)	(3		)	(3		)	—		—
Employer contributions	26			2			8			3			3			—		—
Plan assets at measurement date	$	—		$	—		$	—		$	—		$	—		$	—	$	—

	Year Ended December 31, 2014
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	304		$	15		$	140		$	34		$	39		$	3	$	5
Service cost	3			—			1			1			—			—		—
Interest cost	14			1			5			1			2			—		—
Actuarial losses(a)	43			2			11			2			20			1		1
Settlements	—			—			—			—			—			—		—
Plan amendments	—			—			—			—			—			—		—
Transfers	—			—			(32		)	—			4			—		—
Benefits paid	(27		)	(2		)	(9		)	(3		)	(4		)	—		(1		)
Obligation at measurement date	$	337		$	16		$	116		$	35		$	61		$	4	$	5
Accumulated Benefit Obligation at measurement date	$	333		$	15		$	116		$	35		$	61		$	4	$	5
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	—			—			—			—			—			—		—
Benefits paid	(27		)	(2		)	(9		)	(3		)	(4		)	—		(1		)
Employer contributions	27			2			9			3			4			—		1
Plan assets at measurement date	$	—		$	—		$	—		$	—		$	—		$	—	$	—

(a) Includes an increase in benefit obligation of $21 million as a result of changes in Duke Energy's mortality assumptions.

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2015
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Current pension liability(a)	$	27		$	2	$	8		$	3	$	3	$	—	$	—
Noncurrent pension liability(b)	314			14		104			30		43		4		5
Total accrued pension liability	$	341		$	16	$	112		$	33	$	46	$	4	$	5
Regulatory assets	$	76		$	7	$	16		$	6	$	10	$	1	$	1
Accumulated other comprehensive (income) loss
Deferred income tax liability	$	(3	)	$	—	$	(3	)	$	—	$	—	$	—	$	—
Net actuarial loss	9			—		9			—		—		—		—
Net amounts recognized in accumulated other comprehensive income	$	6		$	—	$	6		$	—	$	—	$	—	$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss	$	8		$	—	$	1		$	—	$	—	$	—	$	—
Unrecognized prior service credit	(1		)	—		—			—		—		—		—

	December 31, 2014
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Current pension liability(a)	$	27		$	2	$	8		$	3	$	4	$	—	$	—
Noncurrent pension liability(b)	310			14		108			32		57		4		5
Total accrued pension liability	$	337		$	16	$	116		$	35	$	61	$	4	$	5
Regulatory assets	$	89		$	5	$	32		$	7	$	25	$	1	$	2
Regulatory liabilities	$	—		$	—	$	—		$	—	$	—	$	—	$	—
Accumulated other comprehensive (income) loss
Deferred income tax asset	$	4		$	—	$	2		$	—	$	—	$	—	$	—
Prior service credit	(1		)	—		—			—		—		—		—
Net actuarial gain	(8		)	—		(4		)	—		—		—		—
Net amounts recognized in accumulated other comprehensive loss	$	(5	)	$	—	$	(2	)	$	—	$	—	$	—	$	—

(a) Included in Other within Current Liabilities on the Consolidated Balance Sheets.

(b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.

Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets

Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets

	December 31, 2015
			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Projected benefit obligation	$	341	$	16	$	112	$	33	$	46	$	4	$	5
Accumulated benefit obligation	336		16		112		33		46		4		5

	December 31, 2014
			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Projected benefit obligation	$	337	$	16	$	116	$	35	$	61	$	4	$	5
Accumulated benefit obligation	333		15		116		35		61		4		5

Assumptions Used for Pension Benefits Accounting

The following tables present the assumptions used for pension benefit accounting.

	December 31,
	2015		2014		2013
Benefit Obligations
Discount rate	4.40	%	4.10	%	4.70	%
Salary increase	4.40	%	4.40	%	4.40	%
Net Periodic Benefit Cost
Discount rate	4.10	%	4.70	%	4.10	%
Salary increase	4.40	%	4.40	%	4.30	%

Expected Benefit Payments

Expected Benefit Payments

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Years ending December 31,
2016	$	28	$	2	$	8	$	3	$	3	$	—	$	—
2017	29		2		8		3		3		—		—
2018	25		2		8		3		3		—		—
2019	26		2		8		3		3		—		—
2020	25		2		8		3		3		—		1
2021 - 2025	126		9		38		12		16		1		2

Other Post-Retirement Benefit Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

Components of Net Periodic Other Post-Retirement Benefit Costs

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	6		$	1		$	1		$	1		$	1		$	—		$	1
Interest cost on accumulated post-retirement benefit obligation	36			9			15			8			7			2			4
Expected return on plan assets	(13		)	(8		)	—			—			—			(1		)	(1		)
Amortization of actuarial loss (gain)	16			(2		)	28			18			10			(2		)	(2		)
Amortization of prior service credit	(140		)	(14		)	(102		)	(68		)	(35		)	—			—
Net periodic post-retirement benefit costs(a)(b)	$	(95	)	$	(14	)	$	(58	)	$	(41	)	$	(17	)	$	(1	)	$	2

	Year Ended December 31, 2014
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	10		$	2		$	4		$	1		$	3		$	—		$	1
Interest cost on accumulated post-retirement benefit obligation	49			12			22			11			12			2			5
Expected return on plan assets	(13		)	(9		)	—			—			—			—			(1		)
Amortization of actuarial loss (gain)	39			3			42			31			10			(2		)	—
Amortization of prior service credit	(125		)	(11		)	(95		)	(73		)	(21		)	—			—
Net periodic post-retirement benefit costs(a)(b)	$	(40	)	$	(3	)	$	(27	)	$	(30	)	$	4		$	—		$	5

	Year Ended December 31, 2013
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	24		$	2		$	18		$	9		$	7		$	1		$	1
Interest cost on accumulated post-retirement benefit obligation	68			13			41			22			16			2			5
Expected return on plan assets	(14		)	(11		)	—			—			—			(1		)	(1		)
Amortization of actuarial loss (gain)	52			3			57			34			16			(1		)	1
Amortization of prior service credit	(41		)	(7		)	(30		)	(20		)	(6		)	(1		)	—
Net periodic post-retirement benefit costs(a)(b)	$	89		$	—		$	86		$	45		$	33		$	—		$	6

(a) Duke Energy amounts exclude $10 million, $9 million, and $8 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

(b) Duke Energy Ohio amounts exclude $3 million, $2 million, and $2 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

Amounts Recognized in AOCI and Regulatory Assets and Liabilities

Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana
Regulatory assets, net increase (decrease)	$	1		$	—		$	1		$	—		$	1		$	—	$	(7	)
Regulatory liabilities, net increase (decrease)	$	(92	)	$	(8	)	$	(71	)	$	(36	)	$	(35	)	$	2	$	(8	)
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	2		$	—		$	(1	)	$	—		$	—		$	—	$	—
Actuarial losses (gains) arising during the year	(5		)	—			2			—			—			—		—
Transfer with the disposal group	(3		)	—			—			—			—			—		—
Amortization of prior year prior service credit	3			—			(1		)	—			—			—		—
Net amount recognized in accumulated other comprehensive income	$	(3	)	$	—		$	—		$	—		$	—		$	—	$	—

	Year Ended December 31, 2014
				Duke					Duke		Duke			Duke			Duke
	Duke			Energy		Progress			Energy		Energy			Energy			Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida			Ohio			Indiana
Regulatory assets, net increase (decrease)	$	162		$	34	$	129		$	97	$	(4	)	$	—		$	(7	)
Regulatory liabilities, net increase (decrease)	$	249		$	76	$	122		$	61	$	61		$	(2	)	$	14
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	1		$	—	$	1		$	—	$	—		$	—		$	—
Actuarial losses (gains) arising during the year	1			—		(2		)	—		—			—			—
Prior year service credit arising during the year	(6		)	—		—			—		—			—			—
Amortization of prior year prior service credit	2			—		—			—		—			—			—
Net amount recognized in accumulated other comprehensive income	$	(2	)	$	—	$	(1	)	$	—	$	—		$	—		$	—

Reconciliation of Funded Status to Net Amount Recognized

Reconciliation of Funded Status to Accrued Other Post-Retirement Benefit Costs

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Change in Projected Benefit Obligation
Accumulated post-retirement benefit obligation at prior measurement date	$	916		$	220		$	379		$	207		$	170		$	39		$	96
Service cost	6			1			1			1			1			—			1
Interest cost	36			9			15			8			7			2			4
Plan participants' contributions	20			4			7			4			3			1			2
Actuarial (gains) losses	(39		)	(18		)	(1		)	(13		)	11			(3		)	1
Transfers	—			2			—			—			—			—			—
Plan amendments	(9		)	—			—			—			—			(1		)	(4		)
Benefits paid	(100		)	(18		)	(47		)	(19		)	(28		)	(3		)	(13		)
Obligation transferred with the Disposal Group	(3		)	—			—			—			—			—			—
Accrued retiree drug subsidy	1			—			—			—			—			—			—
Accumulated post-retirement benefit obligation at measurement date	$	828		$	200		$	354		$	188		$	164		$	35		$	87
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	227		$	145		$	—		$	(1	)	$	—		$	8		$	23
Actual return on plan assets	(1		)	(1		)	1			1			1			—			(1		)
Benefits paid	(100		)	(18		)	(47		)	(19		)	(28		)	(3		)	(13		)
Employer contributions	62			4			39			15			25			2			8
Plan participants' contributions	20			4			7			4			3			1			2
Plan assets at measurement date	$	208		$	134		$	—		$	—		$	1		$	8		$	19

	Year Ended December 31, 2014
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Change in Projected Benefit Obligation
Accumulated post-retirement benefit obligation at prior measurement date	$	1,106		$	265		$	533		$	233		$	253		$	42		$	118
Service cost	10			2			4			1			3			—			1
Interest cost	49			12			22			11			12			2			5
Plan participants' contributions	25			10			8			4			4			—			2
Actuarial gains(a)	(87		)	(35		)	(19		)	(21		)	—			—			(20		)
Transfers	—			1			(48		)	(2		)	—			(1		)	—
Plan amendments	(85		)	(4		)	(77		)	—			(78		)	(1		)	—
Benefits paid	(103		)	(31		)	(44		)	(19		)	(24		)	(3		)	(10		)
Accrued retiree drug subsidy	1			—			—			—			—			—			—
Accumulated post-retirement benefit obligation at measurement date	$	916		$	220		$	379		$	207		$	170		$	39		$	96
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	214		$	143		$	—		$	—		$	—		$	8		$	18
Actual return on plan assets	18			12			—			—			—			—			2
Benefits paid	(103		)	(31		)	(44		)	(19		)	(24		)	(3		)	(10		)
Transfers	—			(1		)	—			—			—			—			—
Employer contributions	73			12			36			14			20			3			11
Plan participants' contributions	25			10			8			4			4			—			2
Plan assets at measurement date	$	227		$	145		$	—		$	(1	)	$	—		$	8		$	23

(a) Includes an increase in benefit obligation of $7 million as a result of changes in Duke Energy's mortality assumptions.

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Current post-retirement liability(a)	$	37		$	—		$	31		$	16		$	15		$	2		$	—
Noncurrent post-retirement liability(b)	583			66			323			172			149			25			68
Total accrued post-retirement liability	$	620		$	66		$	354		$	188		$	164		$	27		$	68
Regulatory assets	$	1		$	—		$	1		$	—		$	1		$	—		$	57
Regulatory liabilities	$	288		$	68		$	51		$	25		$	26		$	21		$	83
Accumulated other comprehensive (income) loss
Deferred income tax liability	$	7		$	—		$	—		$	—		$	—		$	—		$	—
Prior service credit	(6		)	—			(1		)	—			—			—			—
Net actuarial gain	(13		)	—			—			—			—			—			—
Net amounts recognized in accumulated other comprehensive income	$	(12	)	$	—		$	(1	)	$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss (gain)	$	6		$	(3	)	$	22		$	13		$	9		$	(2	)	$	(2	)
Unrecognized prior service credit	(142		)	(14		)	(103		)	(68		)	(35		)	—			(1		)

	December 31, 2014
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana
Current post-retirement liability(a)	$	35		$	—	$	29		$	16	$	14	$	2	$	—
Noncurrent post-retirement liability(b)	654			75		350			192		156		29		73
Total accrued post-retirement liability	$	689		$	75	$	379		$	208	$	170	$	31	$	73
Regulatory assets	$	—		$	—	$	—		$	—	$	—	$	—	$	64
Regulatory liabilities	$	380		$	76	$	122		$	61	$	61	$	19	$	91
Accumulated other comprehensive (income) loss
Deferred income tax liability	$	5		$	—	$	1		$	—	$	—	$	—	$	—
Prior service credit	(9		)	—		—			—		—		—		—
Net actuarial gain	(5		)	—		(2		)	—		—		—		—
Net amounts recognized in accumulated other comprehensive income	$	(9	)	$	—	$	(1	)	$	—	$	—	$	—	$	—

(a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. 

(b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.

Assumptions Used for Pension Benefits Accounting

The following tables present the assumptions used for other post-retirement benefits accounting.

	December 31,
	2015		2014		2013
Benefit Obligations
Discount rate	4.40	%	4.10	%	4.70	%
Net Periodic Benefit Cost
Discount rate	4.10	%	4.70	%	4.10	%
Expected long-term rate of return on plan assets	6.50	%	6.75	%	7.75	%
Assumed tax rate	35	%	35	%	35	%

Assumed Health Care Cost Trend Rate

Assumed Health Care Cost Trend Rate

	December 31,
	2015		2014
Health care cost trend rate assumed for next year	7.50	%	6.75	%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)	4.75	%	4.75	%
Year that rate reaches ultimate trend	2023		2023

Sensitivity to Changes in Assumed Health Care Cost Trend Rates

Sensitivity to Changes in Assumed Health Care Cost Trend Rates

	Year Ended December 31, 2015
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
1-Percentage Point Increase
Effect on total service and interest costs	$	2		$	—		$	1		$	1		$	—		$	—		$	—
Effect on post-retirement benefit obligation	29			7			12			6			6			1			3
1-Percentage Point Decrease
Effect on total service and interest costs	(1		)	—			(1		)	(1		)	—			—			—
Effect on post-retirement benefit obligation	(26		)	(6		)	(11		)	(6		)	(5		)	(1		)	(3		)

Expected Benefit Payments

Expected Benefit Payments

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana
Years ending December 31,
2016	$	76	$	16	$	31	$	16	$	15	$	4	$	10
2017	76		17		31		16		15		3		10
2018	74		18		30		16		14		3		9
2019	73		18		29		15		14		3		9
2020	71		18		29		15		13		3		8
2021 – 2025	312		80		129		68		60		14		33