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Investments in Debt and Equity Securities (Tables)

3 Months Ended

Mar. 31, 2018

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	143	$	—	$	—	$	115
Equity securities	2,751		38		4,857		2,805		27		4,914
Corporate debt securities	7		8		549		17		2		570
Municipal bonds	1		5		333		4		3		344
U.S. government bonds	6		18		1,014		11		7		1,027
Other debt securities	—		2		130		—		1		118
Total NDTF Investments	$	2,765	$	71	$	7,026	$	2,837	$	40	$	7,088
Other Investments
Cash and cash equivalents	$	—	$	—	$	15	$	—	$	—	$	15
Equity securities	57		—		130		59		—		123
Corporate debt securities	—		1		64		1		—		57
Municipal bonds	1		1		80		2		1		83
U.S. government bonds	—		1		51		—		—		41
Other debt securities	—		—		48		—		1		44
Total Other Investments	$	58	$	3	$	388	$	62	$	2	$	363
Total Investments	$	2,823	$	74	$	7,414	$	2,899	$	42	$	7,451


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	143	$	—	$	—	$	115
Equity securities	2,751		38		4,857		2,805		27		4,914
Corporate debt securities	7		8		549		17		2		570
Municipal bonds	1		5		333		4		3		344
U.S. government bonds	6		18		1,014		11		7		1,027
Other debt securities	—		2		130		—		1		118
Total NDTF Investments	$	2,765	$	71	$	7,026	$	2,837	$	40	$	7,088
Other Investments
Cash and cash equivalents	$	—	$	—	$	15	$	—	$	—	$	15
Equity securities	57		—		130		59		—		123
Corporate debt securities	—		1		64		1		—		57
Municipal bonds	1		1		80		2		1		83
U.S. government bonds	—		1		51		—		—		41
Other debt securities	—		—		48		—		1		44
Total Other Investments	$	58	$	3	$	388	$	62	$	2	$	363
Total Investments	$	2,823	$	74	$	7,414	$	2,899	$	42	$	7,451


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	143	$	—	$	—	$	115
Equity securities	2,751		38		4,857		2,805		27		4,914
Corporate debt securities	7		8		549		17		2		570
Municipal bonds	1		5		333		4		3		344
U.S. government bonds	6		18		1,014		11		7		1,027
Other debt securities	—		2		130		—		1		118
Total NDTF Investments	$	2,765	$	71	$	7,026	$	2,837	$	40	$	7,088
Other Investments
Cash and cash equivalents	$	—	$	—	$	15	$	—	$	—	$	15
Equity securities	57		—		130		59		—		123
Corporate debt securities	—		1		64		1		—		57
Municipal bonds	1		1		80		2		1		83
U.S. government bonds	—		1		51		—		—		41
Other debt securities	—		—		48		—		1		44
Total Other Investments	$	58	$	3	$	388	$	62	$	2	$	363
Total Investments	$	2,823	$	74	$	7,414	$	2,899	$	42	$	7,451


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	100
Due after one through five years	535
Due after five through 10 years	530
Due after 10 years	1,104
Total	$	2,269

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the three months ended March 31, 2018 and from sales of AFS securities for the three months ended March 31, 2017 were as follows.



	Three Months Ended
(in millions)	March 31, 2018
FV-NI:
Realized gains	$	19
Realized losses	13
AFS:
Realized gains	5
Realized losses	13



	Three Months Ended
(in millions)	March 31, 2017
Realized gains	$	93
Realized losses	62

Duke Energy Carolinas [Member]

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	50	$	—	$	—	$	32
Equity securities	1,502		20		2,669		1,531		12		2,692
Corporate debt securities	3		5		333		9		2		359
Municipal bonds	—		1		69		—		1		60
U.S. government bonds	2		11		494		3		4		503
Other debt securities	—		2		122		—		1		112
Total NDTF Investments	$	1,507	$	39	$	3,737	$	1,543	$	20	$	3,758


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	50	$	—	$	—	$	32
Equity securities	1,502		20		2,669		1,531		12		2,692
Corporate debt securities	3		5		333		9		2		359
Municipal bonds	—		1		69		—		1		60
U.S. government bonds	2		11		494		3		4		503
Other debt securities	—		2		122		—		1		112
Total NDTF Investments	$	1,507	$	39	$	3,737	$	1,543	$	20	$	3,758


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	50	$	—	$	—	$	32
Equity securities	1,502		20		2,669		1,531		12		2,692
Corporate debt securities	3		5		333		9		2		359
Municipal bonds	—		1		69		—		1		60
U.S. government bonds	2		11		494		3		4		503
Other debt securities	—		2		122		—		1		112
Total NDTF Investments	$	1,507	$	39	$	3,737	$	1,543	$	20	$	3,758


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	11
Due after one through five years	178
Due after five through 10 years	285
Due after 10 years	544
Total	$	1,018

Schedule of Realized Gain (Loss)



	Three Months Ended
(in millions)	March 31, 2018
FV-NI:
Realized gains	$	10
Realized losses	5
AFS:
Realized gains	5
Realized losses	10



	Three Months Ended
(in millions)	March 31, 2017
Realized gains	$	66
Realized losses	40

Progress Energy [Member]

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	93	$	—	$	—	$	83
Equity securities	1,249		18		2,188		1,274		15		2,222
Corporate debt securities	4		3		216		8		—		211
Municipal bonds	1		4		264		4		2		284
U.S. government bonds	4		7		520		8		3		524
Other debt securities	—		—		8		—		—		6
Total NDTF Investments	$	1,258	$	32	$	3,289	$	1,294	$	20	$	3,330
Other Investments
Cash and cash equivalents	$	—	$	—	$	10	$	—	$	—	$	12
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	57	$	2	$	—	$	59
Total Investments	$	1,259	$	32	$	3,346	$	1,296	$	20	$	3,389


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	93	$	—	$	—	$	83
Equity securities	1,249		18		2,188		1,274		15		2,222
Corporate debt securities	4		3		216		8		—		211
Municipal bonds	1		4		264		4		2		284
U.S. government bonds	4		7		520		8		3		524
Other debt securities	—		—		8		—		—		6
Total NDTF Investments	$	1,258	$	32	$	3,289	$	1,294	$	20	$	3,330
Other Investments
Cash and cash equivalents	$	—	$	—	$	10	$	—	$	—	$	12
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	57	$	2	$	—	$	59
Total Investments	$	1,259	$	32	$	3,346	$	1,296	$	20	$	3,389


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	93	$	—	$	—	$	83
Equity securities	1,249		18		2,188		1,274		15		2,222
Corporate debt securities	4		3		216		8		—		211
Municipal bonds	1		4		264		4		2		284
U.S. government bonds	4		7		520		8		3		524
Other debt securities	—		—		8		—		—		6
Total NDTF Investments	$	1,258	$	32	$	3,289	$	1,294	$	20	$	3,330
Other Investments
Cash and cash equivalents	$	—	$	—	$	10	$	—	$	—	$	12
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	57	$	2	$	—	$	59
Total Investments	$	1,259	$	32	$	3,346	$	1,296	$	20	$	3,389


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	75
Due after one through five years	300
Due after five through 10 years	198
Due after 10 years	482
Total	$	1,055

Schedule of Realized Gain (Loss)



	Three Months Ended
(in millions)	March 31, 2018
FV-NI:
Realized gains	$	9
Realized losses	8
AFS:
Realized losses	3



	Three Months Ended
(in millions)	March 31, 2017
Realized gains	$	27
Realized losses	21

Duke Energy Progress [Member]

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	59	$	—	$	—	$	50
Equity securities	959		14		1,765		980		12		1,795
Corporate debt securities	3		2		153		6		—		149
Municipal bonds	1		4		263		4		2		283
U.S. government bonds	3		5		326		5		2		310
Other debt securities	—		—		5		—		—		4
Total NDTF Investments	$	966	$	25	$	2,571	$	995	$	16	$	2,591
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	1
Total Other Investments	$	—	$	—	$	1	$	—	$	—	$	1
Total Investments	$	966	$	25	$	2,572	$	995	$	16	$	2,592


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	59	$	—	$	—	$	50
Equity securities	959		14		1,765		980		12		1,795
Corporate debt securities	3		2		153		6		—		149
Municipal bonds	1		4		263		4		2		283
U.S. government bonds	3		5		326		5		2		310
Other debt securities	—		—		5		—		—		4
Total NDTF Investments	$	966	$	25	$	2,571	$	995	$	16	$	2,591
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	1
Total Other Investments	$	—	$	—	$	1	$	—	$	—	$	1
Total Investments	$	966	$	25	$	2,572	$	995	$	16	$	2,592


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	59	$	—	$	—	$	50
Equity securities	959		14		1,765		980		12		1,795
Corporate debt securities	3		2		153		6		—		149
Municipal bonds	1		4		263		4		2		283
U.S. government bonds	3		5		326		5		2		310
Other debt securities	—		—		5		—		—		4
Total NDTF Investments	$	966	$	25	$	2,571	$	995	$	16	$	2,591
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	1
Total Other Investments	$	—	$	—	$	1	$	—	$	—	$	1
Total Investments	$	966	$	25	$	2,572	$	995	$	16	$	2,592


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	19
Due after one through five years	216
Due after five through 10 years	144
Due after 10 years	368
Total	$	747

Schedule of Realized Gain (Loss)



	Three Months Ended
(in millions)	March 31, 2018
FV-NI:
Realized gains	$	8
Realized losses	8
AFS:
Realized losses	2



	Three Months Ended
(in millions)	March 31, 2017
Realized gains	$	24
Realized losses	19

Duke Energy Florida [Member]

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	34	$	—	$	—	$	33
Equity securities	290		4		423		294		3		427
Corporate debt securities	1		1		63		2		—		62
Municipal bonds	—		—		1		—		—		1
U.S. government bonds	1		2		194		3		1		214
Other debt securities	—		—		3		—		—		2
Total NDTF Investments^(b)	$	292	$	7	$	718	$	299	$	4	$	739
Other Investments
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	—	$	1
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	47	$	2	$	—	$	48
Total Investments	$	293	$	7	$	765	$	301	$	4	$	787


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.


(b)	During the three months ended March 31, 2018, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	34	$	—	$	—	$	33
Equity securities	290		4		423		294		3		427
Corporate debt securities	1		1		63		2		—		62
Municipal bonds	—		—		1		—		—		1
U.S. government bonds	1		2		194		3		1		214
Other debt securities	—		—		3		—		—		2
Total NDTF Investments^(b)	$	292	$	7	$	718	$	299	$	4	$	739
Other Investments
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	—	$	1
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	47	$	2	$	—	$	48
Total Investments	$	293	$	7	$	765	$	301	$	4	$	787


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.


(b)	During the three months ended March 31, 2018, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	34	$	—	$	—	$	33
Equity securities	290		4		423		294		3		427
Corporate debt securities	1		1		63		2		—		62
Municipal bonds	—		—		1		—		—		1
U.S. government bonds	1		2		194		3		1		214
Other debt securities	—		—		3		—		—		2
Total NDTF Investments^(b)	$	292	$	7	$	718	$	299	$	4	$	739
Other Investments
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	—	$	1
Municipal bonds	1		—		47		2		—		47
Total Other Investments	$	1	$	—	$	47	$	2	$	—	$	48
Total Investments	$	293	$	7	$	765	$	301	$	4	$	787


(a)	Where regulatory accounting is applied, realized and unrealized gains and losses are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.


(b)	During the three months ended March 31, 2018, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	56
Due after one through five years	84
Due after five through 10 years	54
Due after 10 years	114
Total	$	308

Schedule of Realized Gain (Loss)



	Three Months Ended
(in millions)	March 31, 2018
FV-NI:
Realized gains	$	1
AFS:
Realized losses	1



	Three Months Ended
(in millions)	March 31, 2017
Realized gains	$	3
Realized losses	2

Duke Energy Indiana [Member]

Schedule of Available-for-sale Securities [Line Items]

Debt Securities, Trading, and Equity Securities, FV-NI

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
Investments
Equity securities	$	48	$	—	$	96	$	49	$	—	$	97
Corporate debt securities	—		—		5		—		—		3
Municipal bonds	—		1		26		—		1		28
Total Investments	$	48	$	1	$	127	$	49	$	1	$	128


(a)	Realized and unrealized gains and losses where regulatory accounting is applied are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Debt Securities, Available-for-sale

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
Investments
Equity securities	$	48	$	—	$	96	$	49	$	—	$	97
Corporate debt securities	—		—		5		—		—		3
Municipal bonds	—		1		26		—		1		28
Total Investments	$	48	$	1	$	127	$	49	$	1	$	128


(a)	Realized and unrealized gains and losses where regulatory accounting is applied are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Available-for-sale Securities

The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS.



	March 31, 2018^(a)						December 31, 2017
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses		Value		Gains		Losses		Value
Investments
Equity securities	$	48	$	—	$	96	$	49	$	—	$	97
Corporate debt securities	—		—		5		—		—		3
Municipal bonds	—		1		26		—		1		28
Total Investments	$	48	$	1	$	127	$	49	$	1	$	128


(a)	Realized and unrealized gains and losses where regulatory accounting is applied are deferred as regulatory assets or liabilities, and there is no impact to net income or other comprehensive income until the gain or loss is amortized or collected.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.



(in millions)	March 31, 2018
Due in one year or less	$	3
Due after one through five years	15
Due after five through 10 years	6
Due after 10 years	7
Total	$	31