Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2017

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant.

	Duke Energy				Progress Energy
	December 31,				December 31,
(in millions)	2017		2016		2017		2016
Regulatory Assets
AROs – coal ash	$	4,025	$	3,761	$	1,984	$	1,830
AROs – nuclear and other	852		684		655		569
Accrued pension and OPEB	2,249		2,387		906		882
Retired generation facilities	480		534		386		422
Debt fair value adjustment	1,197		1,313		—		—
Net regulatory asset related to income taxes	—		894		—		231
Storm cost deferrals	531		153		526		148
Nuclear asset securitized balance, net	1,142		1,193		1,142		1,193
Hedge costs deferrals	234		217		94		91
Derivatives – natural gas supply contracts	142		187		—		—
Demand side management (DSM)/Energy efficiency (EE)	530		407		281		278
Grid modernization	39		65		—		—
Vacation accrual	213		196		42		38
Deferred fuel and purchased power	507		156		349		111
Nuclear deferral	119		226		35		134
Post-in-service carrying costs (PISCC) and deferred operating expenses	366		413		38		42
Transmission expansion obligation	46		71		—		—
Manufactured gas plant (MGP)	91		99		—		—
Advanced metering infrastructure (AMI)	362		218		150		—
NCEMPA deferrals	53		51		53		51
East Bend deferrals	45		32		—		—
Deferred pipeline integrity costs	54		36		—		—
Amounts due from customers	64		66		—		—
Other	538		542		110		103
Total regulatory assets	13,879		13,901		6,751		6,123
Less: current portion	1,437		1,023		741		401
Total noncurrent regulatory assets	$	12,442	$	12,878	$	6,010	$	5,722
Regulatory Liabilities
Costs of removal	$	5,968	$	5,613	$	2,537	$	2,198
ARO – nuclear and other	806		461		—		—
Net regulatory liability related to income taxes	8,113		—		2,802		—
Amounts to be refunded to customers	10		45		—		—
Storm reserve	20		83		—		60
Accrued pension and OPEB	146		174		—		—
Deferred fuel and purchased power	47		192		1		81
Other	622		722		179		245
Total regulatory liabilities	15,732		7,290		5,519		2,584
Less: current portion	402		409		213		189
Total noncurrent regulatory liabilities	$	15,330	$	6,881	$	5,306	$	2,395

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant.

	Duke Energy				Progress Energy
	December 31,				December 31,
(in millions)	2017		2016		2017		2016
Regulatory Assets
AROs – coal ash	$	4,025	$	3,761	$	1,984	$	1,830
AROs – nuclear and other	852		684		655		569
Accrued pension and OPEB	2,249		2,387		906		882
Retired generation facilities	480		534		386		422
Debt fair value adjustment	1,197		1,313		—		—
Net regulatory asset related to income taxes	—		894		—		231
Storm cost deferrals	531		153		526		148
Nuclear asset securitized balance, net	1,142		1,193		1,142		1,193
Hedge costs deferrals	234		217		94		91
Derivatives – natural gas supply contracts	142		187		—		—
Demand side management (DSM)/Energy efficiency (EE)	530		407		281		278
Grid modernization	39		65		—		—
Vacation accrual	213		196		42		38
Deferred fuel and purchased power	507		156		349		111
Nuclear deferral	119		226		35		134
Post-in-service carrying costs (PISCC) and deferred operating expenses	366		413		38		42
Transmission expansion obligation	46		71		—		—
Manufactured gas plant (MGP)	91		99		—		—
Advanced metering infrastructure (AMI)	362		218		150		—
NCEMPA deferrals	53		51		53		51
East Bend deferrals	45		32		—		—
Deferred pipeline integrity costs	54		36		—		—
Amounts due from customers	64		66		—		—
Other	538		542		110		103
Total regulatory assets	13,879		13,901		6,751		6,123
Less: current portion	1,437		1,023		741		401
Total noncurrent regulatory assets	$	12,442	$	12,878	$	6,010	$	5,722
Regulatory Liabilities
Costs of removal	$	5,968	$	5,613	$	2,537	$	2,198
ARO – nuclear and other	806		461		—		—
Net regulatory liability related to income taxes	8,113		—		2,802		—
Amounts to be refunded to customers	10		45		—		—
Storm reserve	20		83		—		60
Accrued pension and OPEB	146		174		—		—
Deferred fuel and purchased power	47		192		1		81
Other	622		722		179		245
Total regulatory liabilities	15,732		7,290		5,519		2,584
Less: current portion	402		409		213		189
Total noncurrent regulatory liabilities	$	15,330	$	6,881	$	5,306	$	2,395

Schedule of Potential Plant Retirements

The table below contains the net carrying value of generating facilities planned for retirement or included in recent IRPs as evaluated for potential retirement due to a lack of requisite environmental control equipment. Dollar amounts in the table below are included in Net property, plant and equipment on the Consolidated Balance Sheets as of December 31, 2017, and exclude capitalized asset retirement costs.

		Remaining Net
	Capacity	Book Value
	(in MW)	(in millions)
Duke Energy Carolinas
Allen Steam Station Units 1-3(a)	585	$	163
Progress Energy and Duke Energy Florida
Crystal River Units 1 and 2(b)	873	107
Duke Energy Indiana
Gallagher Units 2 and 4(c)	280	127
Total Duke Energy	1,738	$	397

(a) Duke Energy Carolinas will retire Allen Steam Station Units 1 through 3 by December 31, 2024, as part of the resolution of a lawsuit involving alleged New Source Review violations.

(b) Duke Energy Florida expects to retire these coal units by the end of 2018 to comply with environmental regulations.

(c) Duke Energy Indiana committed to either retire or stop burning coal at Gallagher Units 2 and 4 by December 31, 2022, as part of the settlement of Edwardsport IGCC matters.

Duke Energy Carolinas [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Duke Energy Carolinas' Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	1,645	$	1,536	(i)	(b)
AROs - nuclear and other	—		9
Accrued pension and OPEB	410		481			(j)
Retired generation facilities(c)	29		39		X	2023
Net regulatory asset related to income taxes(d)	—		484
Hedge costs deferrals(c)	109		93		X	2041
DSM/EE	210		122		(h)	(h)
Vacation accrual	83		76		(e)	2018
Deferred fuel and purchased power	140		—		(f)	2018
Nuclear deferral	84		92			2019
PISCC(c)	35		70		X	(b)
AMI	185		172		X	(b)
Other	222		223			(b)
Total regulatory assets	3,152		3,397
Less: current portion	299		238
Total noncurrent regulatory assets	$	2,853	$	3,159
Regulatory Liabilities(a)
Costs of removal(c)	$	2,054	$	2,015	X	(g)
ARO - nuclear and other	806		461			(b)
Net regulatory liability related to income taxes(d)	3,028		—			(b)
Storm reserve(c)	20		22			(b)
Accrued pension and OPEB	44		46			(j)
Deferred fuel and purchased power	46		105		(f)	2018
Other	359		352			(b)
Total regulatory liabilities	6,357		3,001
Less: current portion	126		161
Total noncurrent regulatory liabilities	$	6,231	$	2,840

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Includes regulatory liabilities related to the change in the North Carolina tax rate discussed in Note 22.

(e) Earns a return on outstanding balance in North Carolina.

(f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina.

(g) Recovered over the life of the associated assets.

(h) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism.

(i) Earns a debt return on coal ash expenditures for North Carolina and South Carolina retail customers.

(j) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Duke Energy Carolinas' Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	1,645	$	1,536	(i)	(b)
AROs - nuclear and other	—		9
Accrued pension and OPEB	410		481			(j)
Retired generation facilities(c)	29		39		X	2023
Net regulatory asset related to income taxes(d)	—		484
Hedge costs deferrals(c)	109		93		X	2041
DSM/EE	210		122		(h)	(h)
Vacation accrual	83		76		(e)	2018
Deferred fuel and purchased power	140		—		(f)	2018
Nuclear deferral	84		92			2019
PISCC(c)	35		70		X	(b)
AMI	185		172		X	(b)
Other	222		223			(b)
Total regulatory assets	3,152		3,397
Less: current portion	299		238
Total noncurrent regulatory assets	$	2,853	$	3,159
Regulatory Liabilities(a)
Costs of removal(c)	$	2,054	$	2,015	X	(g)
ARO - nuclear and other	806		461			(b)
Net regulatory liability related to income taxes(d)	3,028		—			(b)
Storm reserve(c)	20		22			(b)
Accrued pension and OPEB	44		46			(j)
Deferred fuel and purchased power	46		105		(f)	2018
Other	359		352			(b)
Total regulatory liabilities	6,357		3,001
Less: current portion	126		161
Total noncurrent regulatory liabilities	$	6,231	$	2,840

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Includes regulatory liabilities related to the change in the North Carolina tax rate discussed in Note 22.

(e) Earns a return on outstanding balance in North Carolina.

(f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina.

(g) Recovered over the life of the associated assets.

(h) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism.

(i) Earns a debt return on coal ash expenditures for North Carolina and South Carolina retail customers.

(j) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Progress Energy [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant.

	Duke Energy				Progress Energy
	December 31,				December 31,
(in millions)	2017		2016		2017		2016
Regulatory Assets
AROs – coal ash	$	4,025	$	3,761	$	1,984	$	1,830
AROs – nuclear and other	852		684		655		569
Accrued pension and OPEB	2,249		2,387		906		882
Retired generation facilities	480		534		386		422
Debt fair value adjustment	1,197		1,313		—		—
Net regulatory asset related to income taxes	—		894		—		231
Storm cost deferrals	531		153		526		148
Nuclear asset securitized balance, net	1,142		1,193		1,142		1,193
Hedge costs deferrals	234		217		94		91
Derivatives – natural gas supply contracts	142		187		—		—
Demand side management (DSM)/Energy efficiency (EE)	530		407		281		278
Grid modernization	39		65		—		—
Vacation accrual	213		196		42		38
Deferred fuel and purchased power	507		156		349		111
Nuclear deferral	119		226		35		134
Post-in-service carrying costs (PISCC) and deferred operating expenses	366		413		38		42
Transmission expansion obligation	46		71		—		—
Manufactured gas plant (MGP)	91		99		—		—
Advanced metering infrastructure (AMI)	362		218		150		—
NCEMPA deferrals	53		51		53		51
East Bend deferrals	45		32		—		—
Deferred pipeline integrity costs	54		36		—		—
Amounts due from customers	64		66		—		—
Other	538		542		110		103
Total regulatory assets	13,879		13,901		6,751		6,123
Less: current portion	1,437		1,023		741		401
Total noncurrent regulatory assets	$	12,442	$	12,878	$	6,010	$	5,722
Regulatory Liabilities
Costs of removal	$	5,968	$	5,613	$	2,537	$	2,198
ARO – nuclear and other	806		461		—		—
Net regulatory liability related to income taxes	8,113		—		2,802		—
Amounts to be refunded to customers	10		45		—		—
Storm reserve	20		83		—		60
Accrued pension and OPEB	146		174		—		—
Deferred fuel and purchased power	47		192		1		81
Other	622		722		179		245
Total regulatory liabilities	15,732		7,290		5,519		2,584
Less: current portion	402		409		213		189
Total noncurrent regulatory liabilities	$	15,330	$	6,881	$	5,306	$	2,395

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant.

	Duke Energy				Progress Energy
	December 31,				December 31,
(in millions)	2017		2016		2017		2016
Regulatory Assets
AROs – coal ash	$	4,025	$	3,761	$	1,984	$	1,830
AROs – nuclear and other	852		684		655		569
Accrued pension and OPEB	2,249		2,387		906		882
Retired generation facilities	480		534		386		422
Debt fair value adjustment	1,197		1,313		—		—
Net regulatory asset related to income taxes	—		894		—		231
Storm cost deferrals	531		153		526		148
Nuclear asset securitized balance, net	1,142		1,193		1,142		1,193
Hedge costs deferrals	234		217		94		91
Derivatives – natural gas supply contracts	142		187		—		—
Demand side management (DSM)/Energy efficiency (EE)	530		407		281		278
Grid modernization	39		65		—		—
Vacation accrual	213		196		42		38
Deferred fuel and purchased power	507		156		349		111
Nuclear deferral	119		226		35		134
Post-in-service carrying costs (PISCC) and deferred operating expenses	366		413		38		42
Transmission expansion obligation	46		71		—		—
Manufactured gas plant (MGP)	91		99		—		—
Advanced metering infrastructure (AMI)	362		218		150		—
NCEMPA deferrals	53		51		53		51
East Bend deferrals	45		32		—		—
Deferred pipeline integrity costs	54		36		—		—
Amounts due from customers	64		66		—		—
Other	538		542		110		103
Total regulatory assets	13,879		13,901		6,751		6,123
Less: current portion	1,437		1,023		741		401
Total noncurrent regulatory assets	$	12,442	$	12,878	$	6,010	$	5,722
Regulatory Liabilities
Costs of removal	$	5,968	$	5,613	$	2,537	$	2,198
ARO – nuclear and other	806		461		—		—
Net regulatory liability related to income taxes	8,113		—		2,802		—
Amounts to be refunded to customers	10		45		—		—
Storm reserve	20		83		—		60
Accrued pension and OPEB	146		174		—		—
Deferred fuel and purchased power	47		192		1		81
Other	622		722		179		245
Total regulatory liabilities	15,732		7,290		5,519		2,584
Less: current portion	402		409		213		189
Total noncurrent regulatory liabilities	$	15,330	$	6,881	$	5,306	$	2,395

Duke Energy Progress [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Duke Energy Progress' Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	1,975	$	1,822	(i)	(b)
AROs - nuclear and other	359		275			(c)
Accrued pension and OPEB	430		423			(l)
Retired generation facilities	170		165		X	2023
Net regulatory asset related to income taxes	—		7			(d)
Storm cost deferrals(e)	150		148		X	(b)
Hedge costs deferrals	64		66			(b)
DSM/EE(f)	264		263		(j)	2018
Vacation accrual	42		38			2018
Deferred fuel and purchased power	130		24		(g)	2018
Nuclear deferral	35		38			2019
PISCC and deferred operating expenses	38		42		X	2054
AMI	75		—			(b)
NCEMPA deferrals	53		51		(h)	2042
Other	74		69			(b)
Total regulatory assets	3,859		3,431
Less: current portion	352		188
Total noncurrent regulatory assets	$	3,507	$	3,243
Regulatory Liabilities(a)
Costs of removal	$	2,122	$	1,840	X	(k)
Net regulatory liability related to income taxes	1,854		—			(b)
Deferred fuel and purchased power	1		64		(g)	2018
Other	161		200			(b)
Total regulatory liabilities	4,138		2,104
Less: current portion	139		158
Total noncurrent regulatory liabilities	$	3,999	$	1,946

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Recovery period for costs related to nuclear facilities runs through the decommissioning period of each unit.

(d) Recovery over the life of the associated assets. Includes regulatory liabilities related to the change in the North Carolina tax rate discussed in Note 22.

(e) South Carolina storm costs are included in rate base.

(f) Included in rate base.

(g) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina.

(h) South Carolina retail allocated costs are earning a return.

(i) Earns a debt return on coal ash expenditures for North Carolina and South Carolina retail customers.

(j) Includes incentives on DSM/EE investments.

(k) Recovered over the life of the associated assets.

(l) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Duke Energy Progress' Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	1,975	$	1,822	(i)	(b)
AROs - nuclear and other	359		275			(c)
Accrued pension and OPEB	430		423			(l)
Retired generation facilities	170		165		X	2023
Net regulatory asset related to income taxes	—		7			(d)
Storm cost deferrals(e)	150		148		X	(b)
Hedge costs deferrals	64		66			(b)
DSM/EE(f)	264		263		(j)	2018
Vacation accrual	42		38			2018
Deferred fuel and purchased power	130		24		(g)	2018
Nuclear deferral	35		38			2019
PISCC and deferred operating expenses	38		42		X	2054
AMI	75		—			(b)
NCEMPA deferrals	53		51		(h)	2042
Other	74		69			(b)
Total regulatory assets	3,859		3,431
Less: current portion	352		188
Total noncurrent regulatory assets	$	3,507	$	3,243
Regulatory Liabilities(a)
Costs of removal	$	2,122	$	1,840	X	(k)
Net regulatory liability related to income taxes	1,854		—			(b)
Deferred fuel and purchased power	1		64		(g)	2018
Other	161		200			(b)
Total regulatory liabilities	4,138		2,104
Less: current portion	139		158
Total noncurrent regulatory liabilities	$	3,999	$	1,946

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Recovery period for costs related to nuclear facilities runs through the decommissioning period of each unit.

(d) Recovery over the life of the associated assets. Includes regulatory liabilities related to the change in the North Carolina tax rate discussed in Note 22.

(e) South Carolina storm costs are included in rate base.

(f) Included in rate base.

(g) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina.

(h) South Carolina retail allocated costs are earning a return.

(i) Earns a debt return on coal ash expenditures for North Carolina and South Carolina retail customers.

(j) Includes incentives on DSM/EE investments.

(k) Recovered over the life of the associated assets.

(l) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Duke Energy Florida [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Duke Energy Florida's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash(c)	$	9	$	8	X	(b)
AROs - nuclear and other(c)	296		294		X	(b)
Accrued pension and OPEB(c)	476		458		X	(h)
Retired generation facilities(c)	216		257		X	(b)
Net regulatory asset related to income taxes(c)	—		224		X	(d)
Storm cost deferrals(c)	376		—		(f)	2021
Nuclear asset securitized balance, net	1,142		1,193			2036
Hedge costs deferrals	30		25			2018
DSM/EE(c)	17		15		X	2018
Deferred fuel and purchased power(c)	219		87		(g)	2019
Nuclear deferral	—		96
AMI(c)	75		—		X	2032
Other	36		36			(b)
Total regulatory assets	2,892		2,693
Less: current portion	389		213
Total noncurrent regulatory assets	$	2,503	$	2,480
Regulatory Liabilities(a)
Costs of removal(c)	$	415	$	358	(e)	(b)
Net regulatory liability related to income taxes(c)	948		—			(b)
Storm reserve(c)	—		60
Deferred fuel and purchased power(c)	—		17		(g)
Other	18		44			(b)
Total regulatory liabilities	1,381		479
Less: current portion	74		31
Total noncurrent regulatory liabilities	$	1,307	$	448

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Certain costs earn a return.

(f) Earns a debt return/interest once collections begin.

(g) Earns commercial paper rate.

(h) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Duke Energy Florida's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash(c)	$	9	$	8	X	(b)
AROs - nuclear and other(c)	296		294		X	(b)
Accrued pension and OPEB(c)	476		458		X	(h)
Retired generation facilities(c)	216		257		X	(b)
Net regulatory asset related to income taxes(c)	—		224		X	(d)
Storm cost deferrals(c)	376		—		(f)	2021
Nuclear asset securitized balance, net	1,142		1,193			2036
Hedge costs deferrals	30		25			2018
DSM/EE(c)	17		15		X	2018
Deferred fuel and purchased power(c)	219		87		(g)	2019
Nuclear deferral	—		96
AMI(c)	75		—		X	2032
Other	36		36			(b)
Total regulatory assets	2,892		2,693
Less: current portion	389		213
Total noncurrent regulatory assets	$	2,503	$	2,480
Regulatory Liabilities(a)
Costs of removal(c)	$	415	$	358	(e)	(b)
Net regulatory liability related to income taxes(c)	948		—			(b)
Storm reserve(c)	—		60
Deferred fuel and purchased power(c)	—		17		(g)
Other	18		44			(b)
Total regulatory liabilities	1,381		479
Less: current portion	74		31
Total noncurrent regulatory liabilities	$	1,307	$	448

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Certain costs earn a return.

(f) Earns a debt return/interest once collections begin.

(g) Earns commercial paper rate.

(h) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Duke Energy Ohio [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Duke Energy Ohio's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	17	$	12	X	(b)
Accrued pension and OPEB	139		135			(g)
Net regulatory asset related to income taxes(c)	—		63			(d)
Storm cost deferrals	5		5			(b)
Hedge costs deferrals	6		7			(b)
DSM/EE	18		6		(f)	(e)
Grid modernization	39		65		X	(e)
Vacation accrual	5		4			2018
Deferred fuel and purchased power	—		5
PISCC and deferred operating expenses(c)	19		20		X	2083
Transmission expansion obligation	50		71			(e)
MGP	91		99			(b)
AMI	6		—			(b)
East Bend deferrals	45		32		X	(b)
Deferred pipeline integrity costs	12		7		X	(b)
Other	42		26			(b)
Total regulatory assets	494		557
Less: current portion	49		37
Total noncurrent regulatory assets	$	445	$	520
Regulatory Liabilities(a)
Costs of removal	$	189	$	212		(d)
Net regulatory liability related to income taxes	688		—			(b)
Accrued pension and OPEB	16		19			(g)
Deferred fuel and purchased power	—		6
Other	34		20			(b)
Total regulatory liabilities	927		257
Less: current portion	36		21
Total noncurrent regulatory liabilities	$	891	$	236

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Recovered via a rider mechanism.

(f) Includes incentives on DSM/EE investments.

(g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Duke Energy Ohio's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	17	$	12	X	(b)
Accrued pension and OPEB	139		135			(g)
Net regulatory asset related to income taxes(c)	—		63			(d)
Storm cost deferrals	5		5			(b)
Hedge costs deferrals	6		7			(b)
DSM/EE	18		6		(f)	(e)
Grid modernization	39		65		X	(e)
Vacation accrual	5		4			2018
Deferred fuel and purchased power	—		5
PISCC and deferred operating expenses(c)	19		20		X	2083
Transmission expansion obligation	50		71			(e)
MGP	91		99			(b)
AMI	6		—			(b)
East Bend deferrals	45		32		X	(b)
Deferred pipeline integrity costs	12		7		X	(b)
Other	42		26			(b)
Total regulatory assets	494		557
Less: current portion	49		37
Total noncurrent regulatory assets	$	445	$	520
Regulatory Liabilities(a)
Costs of removal	$	189	$	212		(d)
Net regulatory liability related to income taxes	688		—			(b)
Accrued pension and OPEB	16		19			(g)
Deferred fuel and purchased power	—		6
Other	34		20			(b)
Total regulatory liabilities	927		257
Less: current portion	36		21
Total noncurrent regulatory liabilities	$	891	$	236

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Recovered via a rider mechanism.

(f) Includes incentives on DSM/EE investments.

(g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule of MISO Exit Fee Obligations

The following table provides a reconciliation of the beginning and ending balance of Duke Energy Ohio’s recorded liability for its exit obligation and share of MTEP costs, excluding MVP, recorded within Other in Current liabilities and Other in Other Noncurrent Liabilities on the Consolidated Balance Sheets. The retail portions of MTEP costs billed by MISO are recovered by Duke Energy Ohio through a non-bypassable rider. As of December 31, 2017, and 2016, $50 million and $71 million are recorded in Regulatory assets on Duke Energy Ohio's Consolidated Balance Sheets, respectively.

			Provisions/			Cash
(in millions)	December 31, 2016		Adjustments			Reductions			December 31, 2017
Duke Energy Ohio	$	90	$	(20	)	$	(4	)	$	66

Duke Energy Indiana [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Duke Energy Indiana's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	380	$	276		(b)
Accrued pension and OPEB	197		222			(g)
Retired generation facilities(c)	65		73		X	2025
Net regulatory asset related to income taxes	—		119			(d)
Hedge costs deferrals	25		26			(b)
DSM/EE	21		—		(e)	(e)
Vacation accrual	11		10			2018
Deferred fuel and purchased power	18		40			2018
PISCC and deferred operating expenses(c)	274		281		X	(b)
Gasification services agreement buyout(f)	—		8
AMI(c)	21		46		X	(b)
Other	131		121			(b)
Total regulatory assets	1,143		1,222
Less: current portion	165		149
Total noncurrent regulatory assets	$	978	$	1,073
Regulatory Liabilities(a)
Costs of removal	$	644	$	660		(d)
Net regulatory liability related to income taxes	998		—			(b)
Amounts to be refunded to customers	10		45			2018
Accrued pension and OPEB	64		72			(g)
Other	31		11			(b)
Total regulatory liabilities	1,747		788
Less: current portion	24		40
Total noncurrent regulatory liabilities	$	1,723	$	748

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Includes incentives on DSM/EE investments and is recovered through a tracker mechanism over a two-year period.

(f) The IURC authorized Duke Energy Indiana to recover costs incurred to buy out a gasification services agreement, including carrying costs through 2017.

(g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Duke Energy Indiana's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - coal ash	$	380	$	276		(b)
Accrued pension and OPEB	197		222			(g)
Retired generation facilities(c)	65		73		X	2025
Net regulatory asset related to income taxes	—		119			(d)
Hedge costs deferrals	25		26			(b)
DSM/EE	21		—		(e)	(e)
Vacation accrual	11		10			2018
Deferred fuel and purchased power	18		40			2018
PISCC and deferred operating expenses(c)	274		281		X	(b)
Gasification services agreement buyout(f)	—		8
AMI(c)	21		46		X	(b)
Other	131		121			(b)
Total regulatory assets	1,143		1,222
Less: current portion	165		149
Total noncurrent regulatory assets	$	978	$	1,073
Regulatory Liabilities(a)
Costs of removal	$	644	$	660		(d)
Net regulatory liability related to income taxes	998		—			(b)
Amounts to be refunded to customers	10		45			2018
Accrued pension and OPEB	64		72			(g)
Other	31		11			(b)
Total regulatory liabilities	1,747		788
Less: current portion	24		40
Total noncurrent regulatory liabilities	$	1,723	$	748

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Includes incentives on DSM/EE investments and is recovered through a tracker mechanism over a two-year period.

(f) The IURC authorized Duke Energy Indiana to recover costs incurred to buy out a gasification services agreement, including carrying costs through 2017.

(g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Piedmont Natural Gas [Member]

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets

The following tables present the regulatory assets and liabilities recorded on Piedmont's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - other	$	15	$	14		(d)
Accrued pension and OPEB(c)	91		166			(f)
Derivatives - gas supply contracts	142		187			(e)
Vacation accrual(c)	10		13			2018
Deferred pipeline integrity costs(c)	42		36			2018
Amount due from customers	64		66		X	(b)
Other	14		15			(b)
Total regulatory assets	378		497
Less: current portion	95		124
Total noncurrent regulatory assets	$	283	$	373
Regulatory Liabilities(a)
Costs of removal	$	544	$	528		(d)
Net regulatory liability related to income taxes	597		80			(b)
Other	3		—			(b)
Total regulatory liabilities	1,144		608
Less: current portion	3		—
Total noncurrent regulatory liabilities	$	1,141	$	608

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Balance will fluctuate with changes in the market. Current contracts extend into 2031.

(f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.

Schedule Of Regulatory Liabilities

The following tables present the regulatory assets and liabilities recorded on Piedmont's Consolidated Balance Sheets.

	December 31,				Earns/Pays	Recovery/Refund
(in millions)	2017		2016		a Return	Period Ends
Regulatory Assets(a)
AROs - other	$	15	$	14		(d)
Accrued pension and OPEB(c)	91		166			(f)
Derivatives - gas supply contracts	142		187			(e)
Vacation accrual(c)	10		13			2018
Deferred pipeline integrity costs(c)	42		36			2018
Amount due from customers	64		66		X	(b)
Other	14		15			(b)
Total regulatory assets	378		497
Less: current portion	95		124
Total noncurrent regulatory assets	$	283	$	373
Regulatory Liabilities(a)
Costs of removal	$	544	$	528		(d)
Net regulatory liability related to income taxes	597		80			(b)
Other	3		—			(b)
Total regulatory liabilities	1,144		608
Less: current portion	3		—
Total noncurrent regulatory liabilities	$	1,141	$	608

(a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted.

(b) The expected recovery or refund period varies or has not been determined.

(c) Included in rate base.

(d) Recovery over the life of the associated assets.

(e) Balance will fluctuate with changes in the market. Current contracts extend into 2031.

(f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 21 for additional detail.