Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

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. Duke Energy does not anticipate making any contributions in 2019. The following table includes information related to the Duke Energy Registrants’ contributions to its 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		Piedmont(a)
Contributions Made:
2018	$	141	$	46	$	45	$	25	$	20	$	—	$	8	$	—
2017	19		—		—		—		—		4		—		11
2016	155		43		43		24		20		5		9

(a) Piedmont contributed $10 million to its U.S. qualified defined benefit pension plan during the two months ended December 31, 2016, and $10 million for the year ended October 31, 2016.

Fair Value and Allocation of Plan Assets

The following tables provide the fair value measurement amounts for VEBA trust assets.

	December 31, 2018
	Total Fair
(in millions)	Value		Level 2
Cash and cash equivalents	$	3	$	3
Real estate	1		1
Equity securities	25		25
Debt securities	20		20
Total assets	$	49	$	49

	December 31, 2017
	Total Fair
(in millions)	Value		Level 2
Cash and cash equivalents	$	8	$	8
Real estate	1		1
Equity securities	28		28
Debt securities	21		21
Total assets	$	58	$	58

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, 2018
	Total Fair										Not
(in millions)	Value			Level 1			Level 2		Level 3		Categorized(b)
Equity securities	$	2,373		$	1,751		$	—	$	—	$	622
Corporate debt securities	4,054			—			4,054		—		—
Short-term investment funds	363			279			84		—		—
Partnership interests	120			—			—		—		120
Hedge funds	226			—			—		—		226
Real estate limited partnerships	144			—			—		—		144
U.S. government securities	961			—			961		—		—
Guaranteed investment contracts	27			—			—		27		—
Governments bonds – foreign	30			—			30		—		—
Cash	28			28			—		—		—
Net pending transactions and other investments	(2		)	(6		)	4		—		—
Total assets(a)	$	8,324		$	2,052		$	5,133	$	27	$	1,112

(a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana, and Piedmont were allocated approximately 27 percent, 31 percent, 15 percent, 16 percent, 5 percent, 7 percent, and 4 percent, respectively, of the Duke Energy Master Retirement Trust at December 31, 2018. Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages.

(b) Certain investments that are measured at fair value using the net asset value per share practical expedient have not been categorized in the fair value hierarchy.

	December 31, 2017
	Total Fair								Not
(in millions)	Value		Level 1		Level 2		Level 3		Categorized(b)
Equity securities	$	2,823	$	1,976	$	—	$	—	$	847
Corporate debt securities	4,694		—		4,694		—		—
Short-term investment funds	246		192		54		—		—
Partnership interests	137		—		—		—		137
Hedge funds	226		—		—		—		226
Real estate limited partnerships	135		—		—		—		135
U.S. government securities	762		—		762		—		—
Guaranteed investment contracts	28		—		—		28		—
Governments bonds – foreign	38		—		38		—		—
Cash	6		6		—		—		—
Government and commercial mortgage backed securities	2		—		2		—		—
Net pending transactions and other investments	17		15		2		—		—
Total assets(a)	$	9,114	$	2,189	$	5,552	$	28	$	1,345

(a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana, and Piedmont were allocated approximately 27 percent, 30 percent, 15 percent, 15 percent, 5 percent, 8 percent, and 4 percent, respectively, of the Duke Energy Master Retirement Trust and Piedmont's Pension assets at December 31, 2017. Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages.

(b) Certain investments that are measured at fair value using the net asset value per share practical expedient have not been categorized in the fair value hierarchy.

The following table presents target and actual asset allocations for the VEBA trusts at December 31, 2018.

			Actual Allocation at
	Target		December 31,
	Allocation		2018		2017
U.S. equity securities	32	%	43	%	41	%
Non-U.S. equity securities	6	%	8	%	8	%
Real estate	2	%	2	%	2	%
Debt securities	45	%	40	%	36	%
Cash	15	%	7	%	13	%
Total	100	%	100	%	100	%

The following table includes the target asset allocations by asset class at December 31, 2018, and the actual asset allocations for the Duke Energy Master Retirement Trust.

			Actual Allocation at
	Target		December 31,
	Allocation		2018		2017
U.S. equity securities	10	%	11	%	11	%
Non-U.S. equity securities	8	%	8	%	8	%
Global equity securities	10	%	10	%	10	%
Global private equity securities	3	%	2	%	2	%
Debt securities	63	%	63	%	63	%
Hedge funds	2	%	2	%	2	%
Real estate and cash	2	%	2	%	2	%
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 Duke Energy Master Retirement Trust qualified pension and other post-retirement assets at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3).

(in millions)	2018			2017(a)
Balance at January 1	$	28		$	38
Sales	(1		)	(2		)
Total gains and other, net	—			1
Transfer of Level 3 assets to other classifications	—			(9		)
Balance at December 31	$	27		$	28

(a) Balance at January 1 includes $9 million associated with Piedmont pension assets.

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		Piedmont(a)
Years ended December 31,
2018	$	213	$	68	$	58	$	40	$	19	$	4	$	10	$	12
2017	179		61		53		37		16		3		9		7
2016	169		57		50		35		15		3		8

(a) Piedmont's pretax employer matching contributions were $1 million and $7 million during the two months ended December 31, 2016, and for the year ended October 31, 2016, respectively.

Pension Plan [Member] | Qualified Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

Components of Net Periodic Pension Costs

	Year Ended December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	182		$	58		$	51		$	29		$	22		$	5		$	11		$	7
Interest cost on projected benefit obligation	299			72			94			43			50			17			23			11
Expected return on plan assets	(559		)	(147		)	(178		)	(85		)	(91		)	(28		)	(42		)	(22		)
Amortization of actuarial loss	132			29			44			21			23			5			10			11
Amortization of prior service credit	(32		)	(8		)	(3		)	(2		)	(1		)	—			(2		)	(10		)
Net periodic pension costs(a)(b)	$	22		$	4		$	8		$	6		$	3		$	(1	)	$	—		$	(3	)

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	159		$	48		$	45		$	26		$	19		$	4		$	9		$	10
Interest cost on projected benefit obligation	328			79			100			47			53			18			26			14
Expected return on plan assets	(545		)	(142		)	(167		)	(82		)	(85		)	(27		)	(42		)	(24		)
Amortization of actuarial loss	146			31			52			23			29			5			12			11
Amortization of prior service credit	(24		)	(8		)	(3		)	(2		)	(1		)	(1		)	(2		)	(2		)
Settlement charge	12			—			—			—			—			—			—			12
Other	8			2			2			1			1			—			1			1
Net periodic pension costs(a)(b)	$	84		$	10		$	29		$	13		$	16		$	(1	)	$	4		$	22

	Year Ended December 31, 2016
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana
Service cost	$	147		$	48		$	42		$	24		$	19		$	4		$	9
Interest cost on projected benefit obligation	335			86			106			49			55			19			28
Expected return on plan assets	(519		)	(142		)	(168		)	(82		)	(84		)	(27		)	(42		)
Amortization of actuarial loss	134			33			51			23			29			4			11
Amortization of prior service credit	(17		)	(8		)	(3		)	(2		)	(1		)	—			(1		)
Settlement charge	3			—			—			—			—			—			—
Other	8			2			3			1			1			1			1
Net periodic pension costs(a)(b)	$	91		$	19		$	31		$	13		$	19		$	1		$	6

(a) Duke Energy amounts exclude $5 million, $7 million and $8 million for the years ended December 2018, 2017 and 2016, 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 $2 million, $3 million and $4 million for the years ended December 2018, 2017 and 2016, 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, 2018
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana		Piedmont
Regulatory assets, net increase (decrease)	$	298		$	170	$	40		$	31	$	9	$	10	$	30	$	8
Accumulated other comprehensive loss (income)
Deferred income tax expense	$	(2	)	—		1			—		—		—		—		—
Amortization of prior year service credit	1			—		—			—		—		—		—		—
Amortization of prior year actuarial losses	10			—		(4		)	—		—		—		—		—
Net amount recognized in accumulated other comprehensive income	$	9		$	—	$	(3	)	$	—	$	—	$	—	$	—	$	—

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana			Piedmont
Regulatory assets, net (decrease) increase	$	(212	)	$	(70	)	$	(49	)	$	(37	)	$	(11	)	$	9	$	(19	)	$	(64	)
Accumulated other comprehensive (income) loss
Deferred income tax expense	$	—		$	—		$	3		$	—		$	—		$	—	$	—		$	—
Prior year service credit arising during the year	1			—			—			—			—			—		—			—
Amortization of prior year actuarial losses	(7		)	—			(7		)	—			—			—		—			—
Net amount recognized in accumulated other comprehensive income	$	(6	)	$	—		$	(4	)	$	—		$	—		$	—	$	—		$	—

Piedmont's regulatory asset net increase was $34 million and $35 million for the two months ended December 31, 2016, and for the year ended October 31, 2016, respectively.

Reconciliation of Funded Status to Net Amount Recognized

Reconciliation of Funded Status to Net Amount Recognized

	Year Ended December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	8,448		$	2,029		$	2,637		$	1,211		$	1,410		$	479		$	669		$	313
Service cost	174			56			49			28			21			5			10			7
Interest cost	299			72			94			43			50			17			23			11
Actuarial gain	(485		)	(44		)	(204		)	(87		)	(114		)	(29		)	(29		)	(18		)
Transfers	—			—			—			—			—			—			—			(16		)
Benefits paid	(567		)	(159		)	(143		)	(70		)	(72		)	(37		)	(55		)	(33		)
Obligation at measurement date	$	7,869		$	1,954		$	2,433		$	1,125		$	1,295		$	435		$	618		$	264
Accumulated Benefit Obligation at measurement date	$	7,818		$	1,954		$	2,404		$	1,125		$	1,265		$	425		$	614		$	264
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	9,003		$	2,372		$	2,814		$	1,366		$	1,429		$	458		$	684		$	368
Employer contributions	141			46			45			25			20			—			8			—
Actual return on plan assets	(344		)	(91		)	(110		)	(53		)	(55		)	(16		)	(26		)	(14		)
Benefits paid	(567		)	(159		)	(143		)	(70		)	(72		)	(37		)	(55		)	(33		)
Transfers	—			—			—			—			—			—			—			(16		)
Plan assets at measurement date	$	8,233		$	2,168		$	2,606		$	1,268		$	1,322		$	405		$	611		$	305
Funded status of plan	$	364		$	214		$	173		$	143		$	27		$	(30	)	$	(7	)	$	41

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	8,131		$	1,952		$	2,512		$	1,158		$	1,323		$	447		$	658		$	344
Service cost	159			48			45			26			19			4			9			10
Interest cost	328			79			100			47			53			18			26			14
Actuarial loss	455			68			158			57			99			35			26			38
Transfers	—			27			(32		)	(2		)	(15		)	12			—			—
Plan amendments	(61		)	—			—			—			—			—			—			(61		)
Benefits paid	(537		)	(145		)	(146		)	(75		)	(69		)	(37		)	(50		)	(5		)
Benefits paid — settlements	(27		)	—			—			—			—			—			—			(27		)
Obligation at measurement date	$	8,448		$	2,029		$	2,637		$	1,211		$	1,410		$	479		$	669		$	313
Accumulated Benefit Obligation at measurement date	$	8,369		$	2,029		$	2,601		$	1,211		$	1,375		$	468		$	652		$	313
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	8,531		$	2,225		$	2,675		$	1,290		$	1,352		$	428		$	657		$	346
Employer contributions	19			—			—			—			—			4			—			11
Actual return on plan assets	1,017			265			317			153			161			51			77			43
Benefits paid	(537		)	(145		)	(146		)	(75		)	(69		)	(37		)	(50		)	(5		)
Benefits paid — settlements	(27		)	—			—			—			—			—			—			(27		)
Transfers	—			27			(32		)	(2		)	(15		)	12			—			—
Plan assets at measurement date	$	9,003		$	2,372		$	2,814		$	1,366		$	1,429		$	458		$	684		$	368
Funded status of plan	$	555		$	343		$	177		$	155		$	19		$	(21	)	$	15		$	55

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Prefunded pension(a)	$	433		$	214		$	242		$	143		$	96		$	24		$	39		$	41
Noncurrent pension liability(b)	$	69		$	—		$	69		$	—		$	69		$	54		$	46		$	—
Net asset (liability) recognized	$	364		$	214		$	173		$	143		$	27		$	(30	)	$	(7	)	$	41
Regulatory assets	$	2,184		$	576		$	796		$	372		$	424		$	100		$	182		$	81
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(43	)	$	—		$	(2	)	$	—		$	—		$	—		$	—		$	—
Prior service credit	(4		)	—			—			—			—			—			—			—
Net actuarial loss	126			—			5			—			—			—			—			—
Net amounts recognized in accumulated other comprehensive loss	$	79		$	—		$	3		$	—		$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension costs in the next year
Unrecognized net actuarial loss	$	97		$	22		$	37		$	13		$	24		$	3		$	5		$	7
Unrecognized prior service credit	(32		)	(8		)	(3		)	(2		)	(1		)	—			(2		)	(9		)

	December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Prefunded pension(a)	$	680		$	343		$	245		$	155		$	87		$	8		$	16		$	55
Noncurrent pension liability(b)	$	125		$	—		$	68		$	—		$	68		$	29		$	1		$	—
Net asset recognized	$	555		$	343		$	177		$	155		$	19		$	(21	)	$	15		$	55
Regulatory assets	$	1,886		$	406		$	756		$	341		$	415		$	90		$	152		$	73
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(41	)	$	—		$	(3	)	$	—		$	—		$	—		$	—		$	—
Prior service credit	(5		)	—			—			—			—			—			—			—
Net actuarial loss	116			—			9			—			—			—			—			—
Net amounts recognized in accumulated other comprehensive loss	$	70		$	—		$	6		$	—		$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension costs in the next year
Unrecognized net actuarial loss	$	132		$	29		$	44		$	21		$	23		$	5		$	7		$	11
Unrecognized prior service credit	$	(32	)	$	(8	)	$	(3	)	$	(2	)	$	(1	)	$	—		$	(2	)	$	(9	)

(a) Included in Other within Other Noncurrent Assets 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, 2018
					Duke		Duke		Duke
	Duke		Progress		Energy		Energy		Energy
(in millions)	Energy		Energy		Florida		Ohio		Indiana
Projected benefit obligation	$	679	$	679	$	679	$	123	$	203
Accumulated benefit obligation	651		651		651		115		199
Fair value of plan assets	610		610		610		69		159

	December 31, 2017
					Duke		Duke
	Duke		Progress		Energy		Energy
(in millions)	Energy		Energy		Florida		Ohio
Projected benefit obligation	$	1,386	$	718	$	718	$	337
Accumulated benefit obligation	1,326		683		683		326
Fair value of plan assets	1,260		650		650		308

Assumptions Used for Pension Benefits Accounting

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

	December 31,
	2018				2017				2016
Benefit Obligations
Discount rate				4.30%				3.60%				4.10%
Salary increase	3.50	%	–	4.00%	3.50	%	–	4.00%	4.00	%	–	4.50%
Net Periodic Benefit Cost
Discount rate				3.60%				4.10%				4.40%
Salary increase	3.50	%	–	4.00%	4.00	%	–	4.50%	4.00	%	–	4.40%
Expected long-term rate of return on plan assets				6.50%	6.50	%	–	6.75%	6.50	%	–	6.75%

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		Piedmont
Years ending December 31,
2019	$	662	$	210	$	179	$	105	$	73	$	33	$	47	$	20
2020	651		177		171		90		80		37		51		24
2021	663		182		177		95		81		37		51		23
2022	662		189		179		94		84		37		49		22
2023	655		185		181		95		85		35		47		22
2024-2028	2,993		794		902		451		447		158		217		96

Pension Plan [Member] | Nonqualified Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

Components of Net Periodic Pension Costs

	Year Ended December 31, 2018
				Duke				Duke		Duke
	Duke			Energy		Progress		Energy		Energy
(in millions)	Energy			Carolinas		Energy		Progress		Florida
Service cost	$	2		$	1	$	—	$	—	$	—
Interest cost on projected benefit obligation	12			—		4		1		2
Amortization of actuarial loss	8			—		2		1		1
Amortization of prior service credit	(2		)	—		—		—		—
Net periodic pension costs	$	20		$	1	$	6	$	2	$	3

	Year Ended December 31, 2017
				Duke				Duke		Duke
	Duke			Energy		Progress		Energy		Energy
(in millions)	Energy			Carolinas		Energy		Progress		Florida
Service cost	$	2		$	1	$	—	$	—	$	—
Interest cost on projected benefit obligation	13			1		5		1		2
Amortization of actuarial loss	8			—		2		1		1
Amortization of prior service credit	(2		)	—		—		—		—
Net periodic pension costs	$	21		$	2	$	7	$	2	$	3

	Year Ended December 31, 2016
				Duke				Duke		Duke
	Duke			Energy		Progress		Energy		Energy
(in millions)	Energy			Carolinas		Energy		Progress		Florida
Service cost	$	2		$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	14			1		5		1		2
Amortization of actuarial loss	8			1		1		1		1
Amortization of prior service credit	(1		)	—		—		—		—
Net periodic pension costs	$	23		$	2	$	6	$	2	$	3

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, 2018
				Duke					Duke			Duke
	Duke			Energy		Progress			Energy			Energy
(in millions)	Energy			Carolinas		Energy			Progress			Florida
Regulatory assets, net (decrease) increase	$	(16	)	$	1	$	(6	)	$	(3	)	$	(3	)
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	1		$	—	$	1		$	—		$	—
Actuarial gain arising during the year	(4		)	—		(3		)	—			—
Net amount recognized in accumulated other comprehensive loss (income)	$	(3	)	$	—	$	(2	)	$	—		$	—

	Year Ended December 31, 2017
				Duke					Duke		Duke
	Duke			Energy			Progress		Energy		Energy
(in millions)	Energy			Carolinas			Energy		Progress		Florida
Regulatory assets, net increase (decrease)	$	5		$	(1	)	$	3	$	1	$	2
Accumulated other comprehensive (income) loss
Prior service credit arising during the year	$	(1	)	$	—		$	—	$	—	$	—
Actuarial loss arising during the year	2			—			—		—		—
Net amount recognized in accumulated other comprehensive loss (income)	$	1		$	—		$	—	$	—	$	—

Reconciliation of Funded Status to Net Amount Recognized

Reconciliation of Funded Status to Net Amount Recognized

	Year Ended December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana		Piedmont
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	331		$	14		$	116		$	35		$	47		$	4		$	3	$	4
Service cost	2			1			—			—			—			—			—		—
Interest cost	12			—			4			1			2			—			—		—
Actuarial gain	(17		)	—			(6		)	(2		)	(3		)	(1		)	—		(1		)
Benefits paid	(24		)	(1		)	(8		)	(3		)	(3		)	—			—		—
Obligation at measurement date	$	304		$	14		$	106		$	31		$	43		$	3		$	3	$	3
Accumulated Benefit Obligation at measurement date	$	304		$	14		$	106		$	31		$	43		$	3		$	3	$	3
Change in Fair Value of Plan Assets
Benefits paid	$	(24	)	$	(1	)	$	(8	)	$	(3	)	$	(3	)	$	—		$	—	$	—
Employer contributions	24			1			8			3			3			—			—		—
Plan assets at measurement date	$	—		$	—		$	—		$	—		$	—		$	—		$	—	$	—

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana		Piedmont
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	332		$	14		$	114		$	33		$	46		$	4	$	3	$	4
Service cost	2			1			—			—			—			—		—		—
Interest cost	13			1			5			1			2			—		—		—
Actuarial loss (gain)	15			—			5			4			2			—		—		—
Benefits paid	(31		)	(2		)	(8		)	(3		)	(3		)	—		—		—
Obligation at measurement date	$	331		$	14		$	116		$	35		$	47		$	4	$	3	$	4
Accumulated Benefit Obligation at measurement date	$	331		$	14		$	116		$	35		$	47		$	4	$	3	$	4
Change in Fair Value of Plan Assets
Benefits paid	$	(31	)	$	(2	)	$	(8	)	$	(3	)	$	(3	)	$	—	$	—	$	—
Employer contributions	31			2			8			3			3			—		—		—
Plan assets at measurement date	$	—		$	—		$	—		$	—		$	—		$	—	$	—	$	—

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2018
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana		Piedmont
Current pension liability(a)	$	21		$	2	$	8		$	3	$	3	$	—	$	—	$	—
Noncurrent pension liability(b)	283			12		98			28		40		3		3		3
Total accrued pension liability	$	304		$	14	$	106		$	31	$	43	$	3	$	3	$	3
Regulatory assets	$	62		$	5	$	15		$	5	$	10	$	1	$	—	$	1
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(3	)	$	—	$	(2	)	$	—	$	—	$	—	$	—	$	—
Prior service credit	(1		)	—		—			—		—		—		—		—
Net actuarial loss	8			—		6			—		—		—		—		—
Net amounts recognized in accumulated other comprehensive loss	$	4		$	—	$	4		$	—	$	—	$	—	$	—	$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss	$	6		$	—	$	2		$	1	$	1	$	—	$	—	$	—
Unrecognized prior service credit	(2		)	—		—			—		—		—		—		—

	December 31, 2017
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy		Progress			Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida		Ohio		Indiana		Piedmont
Current pension liability(a)	$	23		$	2	$	8		$	3	$	3	$	—	$	—	$	—
Noncurrent pension liability(b)	308			12		108			32		44		4		3		4
Total accrued pension liability	$	331		$	14	$	116		$	35	$	47	$	4	$	3	$	4
Regulatory assets	$	78		$	4	$	21		$	8	$	13	$	1	$	—	$	1
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(4	)	$	—	$	(3	)	$	—	$	—	$	—	$	—	$	—
Prior service credit	(1		)	—		—			—		—		—		—		—
Net actuarial loss	12			—		9			—		—		—		—		—
Net amounts recognized in accumulated other comprehensive loss	$	7		$	—	$	6		$	—	$	—	$	—	$	—	$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss	$	8		$	—	$	2		$	1	$	1	$	—	$	—	$	—
Unrecognized prior service credit	$	(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, 2018
			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana		Piedmont
Projected benefit obligation	$	304	$	14	$	106	$	31	$	43	$	3	$	3	$	3
Accumulated benefit obligation	304		14		106		31		43		3		3		3

	December 31, 2017
			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana		Piedmont
Projected benefit obligation	$	331	$	14	$	116	$	35	$	47	$	4	$	3	$	4
Accumulated benefit obligation	331		14		116		35		47		4		3		4

Assumptions Used for Pension Benefits Accounting

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

	December 31,
	2018					2017					2016
Benefit Obligations
Discount rate				4.30	%				3.60	%	4.10	%
Salary increase	3.50	%	–	4.00	%	3.50	%	–	4.00	%	4.40	%
Net Periodic Benefit Cost
Discount rate				3.60	%				4.10	%	4.40	%
Salary increase	3.50	%	–	4.00	%				4.40	%	4.40	%

	Piedmont
	Two Months Ended		Year Ended
	December 31, 2016		October 31, 2016
Benefit Obligations
Discount rate	4.10	%	3.80	%
Net Periodic Benefit Cost
Discount rate	3.80	%	3.85	%

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		Piedmont
Years ending December 31,
2019	$	22	$	2	$	8	$	3	$	3	$	—	$	—	$	—
2020	21		1		8		2		3		—		—		—
2021	23		1		8		2		3		—		—		—
2022	25		1		8		2		3		—		—		—
2023	25		3		7		2		3		—		—		—
2024-2028	125		10		37		11		15		1		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, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	6		$	1		$	1		$	—		$	1		$	1		$	1		$	1
Interest cost on accumulated post-retirement benefit obligation	28			7			12			6			6			1			3			1
Expected return on plan assets	(13		)	(8		)	—			—			—			—			—			(2		)
Amortization of actuarial loss	6			3			1			1			—			—			4			—
Amortization of prior service credit	(19		)	(5		)	(8		)	(1		)	(7		)	(1		)	(1		)	(2		)
Net periodic post-retirement benefit costs (a)(b)	$	8		$	(2	)	$	6		$	6		$	—		$	1		$	7		$	(2	)

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	4		$	1		$	—		$	—		$	—		$	—		$	—		$	1
Interest cost on accumulated post-retirement benefit obligation	34			8			13			7			6			1			3			1
Expected return on plan assets	(14		)	(8		)	—			—			—			—			(1		)	(2		)
Amortization of actuarial loss (gain)	10			(2		)	21			12			9			(2		)	(1		)	1
Amortization of prior service credit	(115		)	(10		)	(84		)	(54		)	(30		)	—			(1		)	—
Curtailment credit (c)	(30		)	(4		)	(16		)	—			(16		)	(2		)	(2		)	—
Net periodic post-retirement benefit costs(a)(b)	$	(111	)	$	(15	)	$	(66	)	$	(35	)	$	(31	)	$	(3	)	$	(2	)	$	1

	Year Ended December 31, 2016
				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		$	—		$	1		$	—		$	—
Interest cost on accumulated post-retirement benefit obligation	35			8			15			8			7			1			4
Expected return on plan assets	(12		)	(8		)	—			—			—			—			(1		)
Amortization of actuarial loss (gain)	6			(3		)	22			13			9			(2		)	(1		)
Amortization of prior service credit	(141		)	(14		)	(103		)	(68		)	(35		)	—			(1		)
Net periodic post-retirement benefit costs(a)(b)	$	(109	)	$	(16	)	$	(65	)	$	(47	)	$	(18	)	$	(1	)	$	1

(a) Duke Energy amounts exclude $7 million, $7 million and $8 million for the years ended December 2018, 2017 and 2016, 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 $2 million, $2 million and $2 million for the years ended December 2018, 2017 and 2016, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

(c) Curtailment credit resulted from a reduction in average future service of plan participants due to a plan amendment.

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, 2018
				Duke					Duke		Duke		Duke		Duke
	Duke			Energy			Progress		Energy		Energy		Energy		Energy
(in millions)	Energy			Carolinas			Energy		Progress		Florida		Ohio		Indiana			Piedmont
Regulatory assets, net increase (decrease)	$	137		$	—		$	133	$	84	$	49	$	—	$	(5	)	$	4
Regulatory liabilities, net increase (decrease)	$	154		$	(6	)	$	149	$	93	$	56	$	2	$	3		$	—
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(1	)	$	—		$	—	$	—	$	—	$	—	$	—		$	—
Amortization of prior year actuarial gain	1			—			—		—		—		—		—			—
Net amount recognized in accumulated other comprehensive income	$	—		$	—		$	—	$	—	$	—	$	—	$	—		$	—

	Year Ended December 31, 2017
				Duke					Duke		Duke		Duke			Duke
	Duke			Energy			Progress		Energy		Energy		Energy			Energy
(in millions)	Energy			Carolinas			Energy		Progress		Florida		Ohio			Indiana			Piedmont
Regulatory assets, net increase (decrease)	$	71		$	—		$	81	$	42	$	39	$	—		$	(5	)	$	(11	)
Regulatory liabilities, net increase (decrease)	$	(27	)	$	(2	)	$	—	$	—	$	—	$	(3	)	$	(7	)	$	—
Accumulated other comprehensive (income) loss
Deferred income tax benefit	$	(1	)	$	—		$	—	$	—	$	—	$	—		$	—		$	—
Amortization of prior year prior service credit	3			—			—		—		—		—			—			—
Net amount recognized in accumulated other comprehensive income	$	2		$	—		$	—	$	—	$	—	$	—		$	—		$	—

Piedmont's regulatory assets net decreased $1 million for the two months ended December 31, 2016, and increased $2 million for the year ended October 31, 2016.

Reconciliation of Funded Status to Net Amount Recognized

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

	Year Ended December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Change in Projected Benefit Obligation
Accumulated post-retirement benefit obligation at prior measurement date	$	813		$	189		$	342		$	184		$	156		$	30		$	78		$	32
Service cost	6			1			1			—			1			1			1			1
Interest cost	28			7			12			6			6			1			3			1
Plan participants' contributions	18			3			6			4			3			1			2			—
Actuarial gains	(51		)	(8		)	(23		)	(9		)	(13		)	(2		)	(5		)	(1		)
Transfers	—			—			—			—			—			—			—			(1		)
Benefits paid	(86		)	(18		)	(35		)	(19		)	(16		)	(2		)	(12		)	(2		)
Accumulated post-retirement benefit obligation at measurement date	$	728		$	174		$	303		$	166		$	137		$	29		$	67		$	30
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	225		$	133		$	—		$	—		$	—		$	7		$	11		$	31
Actual return on plan assets	(8		)	(5		)	—			—			—			—			—			(1		)
Benefits paid	(86		)	(18		)	(35		)	(19		)	(16		)	(2		)	(12		)	(2		)
Employer contributions	46			2			29			15			13			2			4			1
Plan participants' contributions	18			3			6			4			3			1			2			—
Plan assets at measurement date	$	195		$	115		$	—		$	—		$	—		$	8		$	5		$	29
Funded status of plan	$	(533	)	$	(59	)	$	(303	)	$	(166	)	$	(137	)	$	(21	)	$	(62	)	$	(1	)

	Year Ended December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Change in Projected Benefit Obligation
Accumulated post-retirement benefit obligation at prior measurement date	$	868		$	201		$	357		$	191		$	164		$	32		$	83		$	39
Service cost	4			1			—			—			—			—			—			1
Interest cost	34			8			13			7			6			1			3			1
Plan participants' contributions	17			3			6			3			3			1			2			—
Actuarial losses (gains)	4			(3		)	4			1			3			—			3			1
Transfers	—			2			(1		)	—			(1		)	1			—			—
Plan amendments	(28		)	(5		)	(3		)	(1		)	(2		)	(2		)	(2		)	(9		)
Benefits paid	(86		)	(18		)	(34		)	(17		)	(17		)	(3		)	(11		)	(1		)
Accumulated post-retirement benefit obligation at measurement date	$	813		$	189		$	342		$	184		$	156		$	30		$	78		$	32
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	244		$	137		$	1		$	—		$	—		$	7		$	22		$	29
Actual return on plan assets	25			15			1			—			—			2			1			3
Benefits paid	(86		)	(18		)	(34		)	(17		)	(17		)	(3		)	(11		)	(1		)
Employer contributions (reimbursements)	25			(4		)	26			14			14			—			(3		)	—
Plan participants' contributions	17			3			6			3			3			1			2			—
Plan assets at measurement date	$	225		$	133		$	—		$	—		$	—		$	7		$	11		$	31
Funded status of plan	$	(588	)	$	(56	)	$	(342	)	$	(184	)	$	(156	)	$	(23	)	$	(67	)	$	(1	)

Amounts Recognized in the Consolidated Balance Sheet

Amounts Recognized in the Consolidated Balance Sheets

	December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Current post-retirement liability(a)	$	8		$	—		$	5		$	3		$	2		$	2		$	—		$	—
Noncurrent post-retirement liability(b)	525			59			298			163			135			19			62			1
Total accrued post-retirement liability	$	533		$	59		$	303		$	166		$	137		$	21		$	62		$	1
Regulatory assets	$	262		$	—		$	262		$	164		$	98		$	—		$	41		$	—
Regulatory liabilities	$	301		$	38		$	149		$	93		$	56		$	18		$	67		$	—
Accumulated other comprehensive (income) loss
Deferred income tax expense	$	3		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Prior service credit	(2		)	—			—			—			—			—			—			—
Net actuarial gain	(9		)	—			—			—			—			—			—			—
Net amounts recognized in accumulated other comprehensive income	$	(8	)	$	—		$	—		$	—		$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss	$	4		$	2		$	1		$	—		$	—		$	—		$	—		$	—
Unrecognized prior service credit	(19		)	(5		)	(7		)	(1		)	(6		)	(1		)	(1		)	(2		)

	December 31, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Current post-retirement liability(a)	$	36		$	—		$	29		$	15		$	14		$	2		$	—		$	—
Noncurrent post-retirement liability(b)	552			56			313			169			142			21			67			1
Total accrued post-retirement liability	$	588		$	56		$	342		$	184		$	156		$	23		$	67		$	1
Regulatory assets	$	125		$	—		$	129		$	80		$	49		$	—		$	46		$	(4	)
Regulatory liabilities	$	147		$	44		$	—		$	—		$	—		$	16		$	64		$	—
Accumulated other comprehensive (income) loss
Deferred income tax expense	$	4		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Prior service credit	(2		)	—			—			—			—			—			—			—
Net actuarial gain	(10		)	—			—			—			—			—			—			—
Net amounts recognized in accumulated other comprehensive income	$	(8	)	$	—		$	—		$	—		$	—		$	—		$	—		$	—
Amounts to be recognized in net periodic pension expense in the next year
Unrecognized net actuarial loss (gain)	$	5		$	3		$	1		$	—		$	1		$	—		$	—		$	—
Unrecognized prior service credit	(19		)	(5		)	(7		)	(1		)	(6		)	(1		)	(1		)	(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.

Assumptions Used for Pension Benefits Accounting

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

	December 31,
	2018		2017		2016
Benefit Obligations
Discount rate	4.30	%	3.60	%	4.10	%
Net Periodic Benefit Cost
Discount rate	3.60	%	4.10	%	4.40	%
Expected long-term rate of return on plan assets	6.50	%	6.50	%	6.50	%
Assumed tax rate	35	%	35	%	35	%

	Piedmont
	Two Months Ended		Year Ended
	December 31, 2016		October 31, 2016
Benefit Obligations
Discount rate	4.10	%	3.80	%
Net Periodic Benefit Cost
Discount rate	3.80	%	4.38	%
Expected long-term rate of return on plan assets	6.75	%	7.25	%

Assumed Health Care Cost Trend Rate

Assumed Health Care Cost Trend Rate

	December 31,
	2018		2017
Health care cost trend rate assumed for next year	6.50	%	7.00	%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)	4.75	%	4.75	%
Year that rate reaches ultimate trend	2024		2024

Sensitivity to Changes in Assumed Health Care Cost Trend Rates

Sensitivity to Changes in Assumed Health Care Cost Trend Rates

	Year Ended December 31, 2018
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
1-Percentage Point Increase
Effect on total service and interest costs	$	1		$	—		$	1		$	1		$	—		$	—		$	—		$	—
Effect on post-retirement benefit obligation	22			5			9			5			4			1			2			1
1-Percentage Point Decrease
Effect on total service and interest costs	(1		)	—			(1		)	(1		)	—			—			—			—
Effect on post-retirement benefit obligation	(20		)	(5		)	(8		)	(5		)	(4		)	(1		)	(2		)	(1		)

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		Piedmont
Years ending December 31,
2019	$	81	$	19	$	30	$	16	$	14	$	3	$	9	$	2
2020	75		18		29		15		13		3		8		2
2021	71		18		28		15		13		3		7		2
2022	68		17		27		14		12		3		7		3
2023	64		16		26		14		12		3		6		3
2024-2028	266		64		109		59		50		11		26		12

Piedmont Natural Gas [Member] | Pension Plan [Member] | Qualified Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

	Piedmont
	Two Months Ended			Year Ended
(in millions)	December 31, 2016			October 31, 2016
Service cost	$	2		$	11
Interest cost on projected benefit obligation	2			9
Expected return on plan assets	(4		)	(24		)
Amortization of actuarial loss	2			8
Amortization of prior service credit	(1		)	(2		)
Settlement charge	3			—
Net periodic pension costs	$	4		$	2

Assumptions Used for Pension Benefits Accounting

	Piedmont
	Two Months Ended		Year Ended
	December 31, 2016		October 31, 2016
Benefit Obligations
Discount rate	4.10	%	3.80	%
Salary increase	4.50	%	4.05	%
Net Periodic Benefit Cost
Discount rate	3.80	%	4.34	%
Salary increase	4.05	%	4.07	%
Expected long-term rate of return on plan assets	6.75	%	7.25	%

Piedmont Natural Gas [Member] | Pension Plan [Member] | Nonqualified Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

	Piedmont
	Year Ended
(in millions)	October 31, 2016
Amortization of prior service cost	$	—
Settlement charge	1
Net periodic pension costs	$	1

Assumptions Used for Pension Benefits Accounting

	Piedmont
	Two Months Ended		Year Ended
	December 31, 2016		October 31, 2016
Benefit Obligations
Discount rate	4.10	%	3.80	%
Net Periodic Benefit Cost
Discount rate	3.80	%	3.85	%

Piedmont Natural Gas [Member] | Other Post-Retirement Benefit Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

	Piedmont
	Year Ended
(in millions)	October 31, 2016
Service cost	$	1
Interest cost on projected benefit obligation	1
Expected return on plan assets	(2		)
Amortization of actuarial loss	1
Net periodic pension costs	$	1