Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Line Items]

Schedule of Components of Income Tax Expense (Benefit)

Components of Income Tax Expense

	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
Current income taxes
Federal	$	(647	)	$	(8	)	$	(135	)	$	(71	)	$	(49	)	$	20		$	29	$	67
State	(11		)	6			(5		)	(5		)	(10		)	(1		)	3		1
Foreign	3			—			—			—			—			—			—		—
Total current income taxes	(655		)	(2		)	(140		)	(76		)	(59		)	19			32		68
Deferred income taxes
Federal	1,064			299			341			256			115			21			74		(36		)
State	49			11			20			(17		)	45			3			22		5
Total deferred income taxes(a)(b)	1,113			310			361			239			160			24			96		(31		)
Investment tax credit amortization	(10		)	(5		)	(3		)	(3		)	—			—			—		—
Income tax expense from continuing operations	448			303			218			160			101			43			128		37
Tax benefit from discontinued operations	(26		)	—			—			—			—			—			—		—
Total income tax expense included in Consolidated Statements of Operations	$	422		$	303		$	218		$	160		$	101		$	43		$	128	$	37

(a) Includes benefits of NOL carryforwards and tax credit carryforwards of $22 million at Duke Energy Carolinas, $293 million at Progress Energy, $59 million at Duke Energy Progress, $219 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $21 million at Duke Energy Indiana and $39 million at Piedmont. In addition, total deferred income taxes includes utilization of NOL carryforwards and tax credit carryforwards of $18 million at Duke Energy.

(b) For the year ended December 31, 2018, the Company has revised the December 31, 2017, estimates of the income tax effects of the Tax Act, in accordance with SAB 118. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense.

	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
Current income taxes
Federal	$	(247	)	$	221		$	(436	)	$	(95	)	$	(188	)	$	(37	)	$	128	$	(90	)
State	4			20			(5		)	2			(11		)	2			21		(3		)
Foreign	3			—			—			—			—			—			—		—
Total current income taxes	(240		)	241			(441		)	(93		)	(199		)	(35		)	149		(93		)
Deferred income taxes
Federal	1,344			381			664			378			194			99			138		147
State	102			35			44			10			51			(4		)	14		8
Total deferred income taxes(a)(b)	1,446			416			708			388			245			95			152		155
Investment tax credit amortization	(10		)	(5		)	(3		)	(3		)	—			(1		)	—		—
Income tax expense from continuing operations	1,196			652			264			292			46			59			301		62
Tax benefit from discontinued operations	(6		)	—			—			—			—			—			—		—
Total income tax expense included in Consolidated Statements of Operations	$	1,190		$	652		$	264		$	292		$	46		$	59		$	301	$	62

(a) Includes utilization of NOL carryforwards and tax credit carryforwards of $428 million at Duke Energy, $74 million at Progress Energy, $36 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $42 million at Duke Energy Indiana and $79 million at Piedmont. In addition, total deferred income taxes includes benefits of NOL carryforwards and tax credit carryforwards of $10 million at Duke Energy Carolinas and $1 million at Duke Energy Progress.

(b) As a result of the Tax Act, Duke Energy's deferred tax assets and liabilities were revalued as of December 31, 2017. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense.

	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
Current income taxes
Federal	$	—		$	139		$	15		$	(59	)	$	76	$	(7	)	$	7
State	(15		)	25			(19		)	(25		)	22		(13		)	6
Foreign	2			—			—			—			—		—			—
Total current income taxes	(13		)	164			(4		)	(84		)	98		(20		)	13
Deferred income taxes
Federal	1,064			430			486			350			199		88			202
State	117			45			50			40			25		11			11
Total deferred income taxes(a)	1,181			475			536			390			224		99			213
Investment tax credit amortization	(12		)	(5		)	(5		)	(5		)	—		(1		)	(1		)
Income tax expense from continuing operations	1,156			634			527			301			322		78			225
Tax (benefit) expense from discontinued operations	(30		)	—			1			—			—		(36		)	—
Total income tax expense included in Consolidated Statements of Operations	$	1,126		$	634		$	528		$	301		$	322	$	42		$	225

(a) Includes benefits of NOL carryforwards and utilization of NOL and tax credit carryforwards of $648 million at Duke Energy, $4 million at Duke Energy Carolinas, $190 million at Progress Energy, $60 million at Duke Energy Progress, $49 million at Duke Energy Florida, $26 million at Duke Energy Ohio and $58 million at Duke Energy Indiana.

	Piedmont
	Two Months Ended			Year Ended October 31,
(in millions)	December 31, 2016			2016
Current income taxes
Federal	$	4		$	27
State	(2		)	12
Total current income taxes	2			39
Deferred income taxes
Federal	24			79
State	6			6
Total deferred income taxes(a)	30			85
Total income tax expense from continuing operations included in Consolidated Statements of Operations	$	32		$	124

Schedule of Income before Income Tax, Domestic and Foreign

Duke Energy Income from Continuing Operations before Income Taxes

	Years Ended December 31,
(in millions)	2018		2017		2016
Domestic(a)	$	3,018	$	4,207	$	3,689
Foreign	55		59		45
Income from continuing operations before income taxes	$	3,073	$	4,266	$	3,734

(a) Includes a $16 million expense in 2017 related to the Tax Act impact on equity earnings included within Equity in earnings (losses) of unconsolidated affiliates on the Consolidated Statement of Operations.

Summary of Effective Tax Rates

The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations.

	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
Income tax expense, computed at the statutory rate of 21 percent	$	645		$	288		$	263		$	174		$	137		$	46		$	109		$	35
State income tax, net of federal income tax effect	30			14			13			(17		)	28			2			20			4
Amortization of excess deferred income tax	(61		)	—			(55		)	(1		)	(54		)	(3		)	(2		)	—
AFUDC equity income	(42		)	(15		)	(22		)	(12		)	(10		)	(2		)	(2		)	—
AFUDC equity depreciation	31			18			9			5			4			1			4			—
Renewable energy production tax credits	(129		)	—			—			—			—			—			—			—
Other tax credits	(28		)	(7		)	(13		)	(5		)	(8		)	(1		)	(1		)	(3		)
Tax Act(a)	20			1			25			19			—			2			—			—
Other items, net	(18		)	4			(2		)	(3		)	4			(2		)	—			1
Income tax expense from continuing operations	$	448		$	303		$	218		$	160		$	101		$	43		$	128		$	37
Effective tax rate	14.6		%	22.1		%	17.4		%	19.3		%	15.4		%	19.6		%	24.6		%	22.3		%

(a) For the year ended December 31, 2018, the Company revised the December 31, 2017 estimates of the income tax effects of the Tax Act, in accordance with SAB 118. Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits.

	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
Income tax expense, computed at the statutory rate of 35 percent	$	1,493		$	653		$	536		$	353		$	265		$	88		$	229		$	70
State income tax, net of federal income tax effect	69			36			25			8			26			(1		)	23			3
AFUDC equity income	(81		)	(37		)	(32		)	(17		)	(16		)	(4		)	(8		)	—
Renewable energy production tax credits	(132		)	—			—			—			—			—			—			—
Tax Act(a)	(112		)	15			(246		)	(40		)	(226		)	(23		)	55			(12		)
Tax true up	(52		)	(24		)	(19		)	(13		)	(7		)	(5		)	(6		)	—
Other items, net	11			9			—			1			4			4			8			1
Income tax expense from continuing operations	$	1,196		$	652		$	264		$	292		$	46		$	59		$	301		$	62
Effective tax rate	28.0		%	34.9		%	17.2		%	29.0		%	6.1		%	23.4		%	46.0		%	30.8		%

(a) Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related to abandoned or impaired assets, certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits.

	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
Income tax expense, computed at the statutory rate of 35 percent	$	1,307		$	630		$	548		$	315		$	306		$	95		$	212
State income tax, net of federal income tax effect	64			46			20			10			30			(2		)	11
AFUDC equity income	(70		)	(36		)	(26		)	(17		)	(9		)	(2		)	(6		)
Renewable energy production tax credits	(97		)	—			—			—			—			—			—
Audit adjustment	5			3			—			—			—			—			—
Tax true up	(14		)	(14		)	(11		)	(3		)	(9		)	(16		)	2
Other items, net	(39		)	5			(4		)	(4		)	4			3			6
Income tax expense from continuing operations	$	1,156		$	634		$	527		$	301		$	322		$	78		$	225
Effective tax rate	31.0		%	35.2		%	33.7		%	33.4		%	36.9		%	28.9		%	37.1		%

Schedule of Deferred Tax Assets and Liabilities

	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
Deferred credits and other liabilities	$	143		$	33		$	78		$	23		$	49		$	11		$	6		$	(5	)
Capital lease obligations	49			14			—			—			—			—			2			—
Pension, post-retirement and other employee benefits	295			(17		)	111			44			60			14			18			(4		)
Progress Energy merger purchase accounting adjustments(a)	536			—			—			—			—			—			—			—
Tax credits and NOL carryforwards	4,527			234			402			156			143			25			216			70
Regulatory liabilities and deferred credits	—			222			—			—			—			65			—			61
Investments and other assets	—			—			—			—			—			—			1			18
Other	73			10			1			4			—			—			—			—
Valuation allowance	(519		)	—			(14		)	—			—			—			—			—
Total deferred income tax assets	5,104			496			578			227			252			115			243			140
Investments and other assets	(1,419		)	(849		)	(470		)	(289		)	(187		)	—			(14		)	—
Accelerated depreciation rates	(9,216		)	(3,060		)	(2,803		)	(1,583		)	(1,257		)	(896		)	(966		)	(697		)
Regulatory assets and deferred debits, net	(1,090		)	—			(807		)	(238		)	(569		)	—			(188		)	—
Other	—			—			—			—			—			—			—			(7		)
Total deferred income tax liabilities	(11,725		)	(3,909		)	(4,080		)	(2,110		)	(2,013		)	(896		)	(1,168		)	(704		)
Net deferred income tax liabilities	$	(6,621	)	$	(3,413	)	$	(3,502	)	$	(1,883	)	$	(1,761	)	$	(781	)	$	(925	)	$	(564	)

(a) Primarily related to capital lease obligations and debt fair value adjustments.

Net Deferred Income Tax Liability Components

	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
Deferred credits and other liabilities	$	164		$	64		$	35		$	53		$	—		$	17		$	6		$	17
Capital lease obligations	60			26			—			—			—			—			2			—
Pension, post-retirement and other employee benefits	347			24			110			47			58			16			24			(1		)
Progress Energy merger purchase accounting adjustments(a)	483			—			—			—			—			—			—			—
Tax credits and NOL carryforwards	4,580			257			693			215			363			42			237			110
Regulatory liabilities and deferred credits	—			—			—			—			—			56			—			48
Investments and other assets	—			—			—			—			—			18			—			16
Other	25			6			5			5			—			1			(1		)	—
Valuation allowance	(484		)	—			—			—			—			—			—			—
Total deferred income tax assets	5,175			377			843			320			421			150			268			190
Investments and other assets	(1,317		)	(795		)	(430		)	(272		)	(163		)	—			(5		)	—
Accelerated depreciation rates	(10,124		)	(3,207		)	(3,369		)	(1,735		)	(1,670		)	(967		)	(1,081		)	(733		)
Regulatory assets and deferred debits, net	(1,540		)	(64		)	(985		)	(432		)	(574		)	—			(191		)	—
Other	—			—			—			—			—			—			—			(8		)
Total deferred income tax liabilities	(12,981		)	(4,066		)	(4,784		)	(2,439		)	(2,407		)	(967		)	(1,277		)	(741		)
Net deferred income tax liabilities	$	(7,806	)	$	(3,689	)	$	(3,941	)	$	(2,119	)	$	(1,986	)	$	(817	)	$	(1,009	)	$	(551	)

(a) Primarily related to capital lease obligations and debt fair value adjustments.

Summary of Tax Credit Carryforwards

The following table presents the expiration of tax credits and NOL carryforwards.

	December 31, 2018
(in millions)	Amount		Expiration Year
Investment tax credits	$	1,614	2024	—	2038
Alternative minimum tax credits	574		Refundable by 2021
Federal NOL carryforwards(a)(e)	788		2022	—	Indefinite
State NOL carryforwards and credits(b)(e)	301		2019	—	Indefinite
Foreign NOL carryforwards(c)	12		2027	—	2037
Foreign Tax Credits(d)	1,271		2024	—	2027
Charitable contribution carryforwards	20		2019	—	2023
Total tax credits and NOL carryforwards	$	4,580

(a) A valuation allowance of $4 million has been recorded on the Federal NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.

(b) A valuation allowance of $85 million has been recorded on the state NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.

(c) A valuation allowance of $12 million has been recorded on the foreign NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.

(d) A valuation allowance of $383 million has been recorded on the foreign tax credits, as presented in the Net Deferred Income Tax Liability Components table.

(e) Indefinite carryforward for Federal NOLs, and NOLs for states that have adopted the Tax Act's NOL provisions, generated in tax years beginning after December 31, 2017.

	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
Deferred credits and other liabilities	$	143		$	33		$	78		$	23		$	49		$	11		$	6		$	(5	)
Capital lease obligations	49			14			—			—			—			—			2			—
Pension, post-retirement and other employee benefits	295			(17		)	111			44			60			14			18			(4		)
Progress Energy merger purchase accounting adjustments(a)	536			—			—			—			—			—			—			—
Tax credits and NOL carryforwards	4,527			234			402			156			143			25			216			70
Regulatory liabilities and deferred credits	—			222			—			—			—			65			—			61
Investments and other assets	—			—			—			—			—			—			1			18
Other	73			10			1			4			—			—			—			—
Valuation allowance	(519		)	—			(14		)	—			—			—			—			—
Total deferred income tax assets	5,104			496			578			227			252			115			243			140
Investments and other assets	(1,419		)	(849		)	(470		)	(289		)	(187		)	—			(14		)	—
Accelerated depreciation rates	(9,216		)	(3,060		)	(2,803		)	(1,583		)	(1,257		)	(896		)	(966		)	(697		)
Regulatory assets and deferred debits, net	(1,090		)	—			(807		)	(238		)	(569		)	—			(188		)	—
Other	—			—			—			—			—			—			—			(7		)
Total deferred income tax liabilities	(11,725		)	(3,909		)	(4,080		)	(2,110		)	(2,013		)	(896		)	(1,168		)	(704		)
Net deferred income tax liabilities	$	(6,621	)	$	(3,413	)	$	(3,502	)	$	(1,883	)	$	(1,761	)	$	(781	)	$	(925	)	$	(564	)

Schedule of Unrecognized Tax Benefits Roll Forward

The following tables present changes to unrecognized tax benefits.

	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
Unrecognized tax benefits – January 1	$	25		$	5		$	5	$	5	$	5		$	1	$	1	$	3
Unrecognized tax benefits increases (decreases)
Gross decreases – tax positions in prior periods	(2		)	(1		)	—		—		(4		)	—		—		—
Gross increases – current period tax positions	7			2			4		1		2			—		—		1
Decreases due to settlements	(6		)	—			—		—		—			—		—		—
Total changes	(1		)	1			4		1		(2		)	—		—		1
Unrecognized tax benefits – December 31	$	24		$	6		$	9	$	6	$	3		$	1	$	1	$	4

	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
Unrecognized tax benefits – January 1	$	17		$	1	$	2	$	2	$	4	$	4		$	—	$	—
Unrecognized tax benefits increases (decreases)
Gross increases – tax positions in prior periods	12			4		3		3		1		1			1		3
Gross decreases – tax positions in prior periods	(4		)	—		—		—		—		(4		)	—		—
Total changes	8			4		3		3		1		(3		)	1		3
Unrecognized tax benefits – December 31	$	25		$	5	$	5	$	5	$	5	$	1		$	1	$	3

	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
Unrecognized tax benefits – January 1	$	88		$	72		$	1		$	3		$	—	$	—	$	1
Unrecognized tax benefits increases (decreases)
Gross increases – tax positions in prior periods	—			—			—			—			4		4		—
Gross decreases – tax positions in prior periods	(4		)	(4		)	(1		)	(1		)	—		—		—
Decreases due to settlements	(68		)	(67		)	—			—			—		—		(1		)
Reduction due to lapse of statute of limitations	1			—			2			—			—		—		—
Total changes	(71		)	(71		)	1			(1		)	4		4		(1		)
Unrecognized tax benefits – December 31	$	17		$	1		$	2		$	2		$	4	$	4	$	—

Summary of Income Tax Contingencies

The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits at December 31, 2018. All Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months.

	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
Amount that if recognized, would affect the effective tax rate or regulatory liability(a)	$	21	$	6	$	9	$	6	$	3	$	1	$	1	$	4
Amount that if recognized, would be recorded as a component of discontinued operations	2		—		—		—		—		—		—		—

(a) Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana and Piedmont are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability.

The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets.

	Year Ended December 31, 2018
					Duke
	Duke		Progress		Energy
(in millions)	Energy		Energy		Progress
Net interest income recognized related to income taxes	$	2	$	—	$	—
Interest payable related to income taxes	3		1		1

	Year Ended December 31, 2017
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Net interest income recognized related to income taxes	$	—	$	—	$	1	$	—	$	1
Net interest expense recognized related to income taxes	—		2		—		—		—
Interest payable related to income taxes	5		25		1		1		—

	Year Ended December 31, 2016
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Net interest income recognized related to income taxes	$	—	$	—	$	1	$	—	$	2
Net interest expense recognized related to income taxes	—		7		—		—		—
Interest payable related to income taxes	4		23		1		1		—

Piedmont Natural Gas [Member]

Income Tax Disclosure [Line Items]

Schedule of Components of Income Tax Expense (Benefit)

	Piedmont
	Two Months Ended			Year Ended October 31,
(in millions)	December 31, 2016			2016
Current income taxes
Federal	$	4		$	27
State	(2		)	12
Total current income taxes	2			39
Deferred income taxes
Federal	24			79
State	6			6
Total deferred income taxes(a)	30			85
Total income tax expense from continuing operations included in Consolidated Statements of Operations	$	32		$	124

(a) Includes benefits of NOL and tax carryforwards of $17 million and $91 million for the two months ended December 31, 2016, and the year ended October 31, 2016, respectively.

Summary of Effective Tax Rates

	Piedmont
	Two Months Ended			Year Ended October 31,
(in millions)	December 31, 2016			2016
Income tax expense, computed at the statutory rate of 35 percent	$	30		$	111
State income tax, net of federal income tax effect	1			11
Other items, net	1			2
Income tax expense from continuing operations	$	32		$	124
Effective tax rate	37.2		%	39.1		%