Investments in Debt and Equity Securities (Tables)

9 Months Ended

Sep. 30, 2015

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

Available-for-sale Securities

The following table presents the estimated fair value of investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	156	$	—	$	—	$	136
Equity securities	1,655		71		3,396		1,926		29		3,650
Corporate debt securities	9		7		500		14		2		454
Municipal bonds	4		2		207		5		—		184
U.S. government bonds	23		1		1,131		19		2		978
Other debt securities	1		3		172		1		2		147
Total NDTF(c)	$	1,692	$	84	$	5,562	$	1,965	$	35	$	5,549
Other Investments
Cash and cash equivalents	$	—	$	—	$	32	$	—	$	—	$	15
Equity securities	27		1		90		34		—		96
Corporate debt securities	1		2		98		1		1		58
Municipal bonds	3		1		73		3		1		76
U.S. government bonds	1		—		52		—		—		27
Other debt securities	—		1		69		1		1		80
Total Other Investments(a)	$	32	$	5	$	414	$	39	$	3	$	352
Total Investments	$	1,724	$	89	$	5,976	$	2,004	$	38	$	5,901

(a)    These amounts are recorded in Other with Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts are considered other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

(c) As of September 30, 2015, the estimated fair value of the NDTF includes NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets. Refer to Note 2 for further information. This increase in estimated fair value compared to December 31, 2014, is partially offset due to reimbursements from the NDTF for Duke Energy Florida's 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)	September 30, 2015
Due in one year or less	$	74
Due after one through five years	781
Due after five through 10 years	635
Due after 10 years	812
Total	$	2,302

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	30	$	28	$	160	$	90
Realized losses	28		51		59		57

Duke Energy Carolinas [Member]

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

Available-for-sale Securities

The following table presents the estimated fair value of investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	25	$	—	$	—	$	51
Equity securities	930		42		1,990		1,102		17		2,162
Corporate debt securities	5		6		342		8		2		316
Municipal bonds	1		1		69		1		—		62
U.S. government bonds	6		1		383		7		1		308
Other debt securities	1		3		141		1		2		133
Total NDTF	$	943	$	53	$	2,950	$	1,119	$	22	$	3,032
Other Investments
Other debt securities	$	—	$	1	$	3	$	—	$	1	$	3
Total Other Investments(a)	$	—	$	1	$	3	$	—	$	1	$	3
Total Investments	$	943	$	54	$	2,953	$	1,119	$	23	$	3,035

(a) These amounts are recorded in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.

(in millions)	September 30, 2015
Due in one year or less	$	13
Due after one through five years	209
Due after five through 10 years	293
Due after 10 years	423
Total	$	938

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	25	$	20	$	132	$	72
Realized losses	24		48		47		50

Progress Energy [Member]

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

Available-for-sale Securities

The following table presents the estimated fair value investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	131	$	—	$	—	$	85
Equity securities	725		29		1,406		824		12		1,488
Corporate debt securities	4		1		158		6		—		138
Municipal bonds	3		1		138		4		—		122
U.S. government bonds	17		—		748		12		1		670
Other debt securities	—		—		31		—		—		14
Total NDTF(c)	$	749	$	31	$	2,612	$	846	$	13	$	2,517
Other Investments
Cash and cash equivalents	$	—	$	—	$	23	$	—	$	—	$	15
Municipal bonds	3		—		43		3		—		43
Total Other Investments(a)	$	3	$	—	$	66	$	3	$	—	$	58
Total Investments	$	752	$	31	$	2,678	$	849	$	13	$	2,575

(a)    These amounts are recorded in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

(c) As of September 30, 2015, the estimated fair value of the NDTF includes NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets. Refer to Note 2 for further information. This increase in estimated fair value compared to December 31, 2014, is partially offset due to reimbursements from the NDTF for Duke Energy Florida's 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)	September 30, 2015
Due in one year or less	$	38
Due after one through five years	476
Due after five through 10 years	271
Due after 10 years	333
Total	$	1,118

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	5	$	8	$	26	$	17
Realized losses	4		3		10		6

Duke Energy Progress [Member]

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

Available-for-sale Securities

The following table presents the estimated fair value of investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	87	$	—	$	—	$	50
Equity securities	535		23		1,107		612		10		1,171
Corporate debt securities	3		1		109		5		—		97
Municipal bonds	3		1		136		4		—		120
U.S. government bonds	12		—		485		9		1		265
Other debt securities	—		—		19		—		—		8
Total NDTF (c)	$	553	$	25	$	1,943	$	630	$	11	$	1,711
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	—
Total Other Investments(a)	$	—	$	—	$	1	$	—	$	—	$	—
Total Investments	$	553	$	25	$	1,944	$	630	$	11	$	1,711

(a)    These amounts are recorded in Other with Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

(c) As of September 30, 2015, the estimated fair value of the NDTF includes NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets. Refer to Note 2 for further information.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.

(in millions)	September 30, 2015
Due in one year or less	$	12
Due after one through five years	278
Due after five through 10 years	219
Due after 10 years	240
Total	$	749

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	4	$	4	$	21	$	11
Realized losses	3		2		8		4

Duke Energy Florida [Member]

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

Available-for-sale Securities

The following table presents the estimated fair value of investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
NDTF
Cash and cash equivalents	$	—	$	—	$	44	$	—	$	—	$	35
Equity securities	190		6		299		212		2		317
Corporate debt securities	1		—		49		1		—		41
Municipal bonds	—		—		2		—		—		2
U.S. government bonds	5		—		263		3		—		405
Other debt securities	—		—		12		—		—		6
Total NDTF(c)	$	196	$	6	$	669	$	216	$	2	$	806
Other Investments
Cash and cash equivalents	$	—	$	—	$	11	$	—	$	—	$	1
Municipal bonds	3		—		43		3		—		43
Total Other Investments(a)	$	3	$	—	$	54	$	3	$	—	$	44
Total Investments	$	199	$	6	$	723	$	219	$	2	$	850

(a)    These amounts are recorded in Other with Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

(c) The estimated fair value at September 30, 2015, compared to the balance at December 31, 2014, is lower due to current year 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)	September 30, 2015
Due in one year or less	$	26
Due after one through five years	198
Due after five through 10 years	52
Due after 10 years	93
Total	$	369

Schedule of Realized Gain (Loss)

Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	1	$	3	$	5	$	5
Realized losses	1		1		2		2

Duke Energy Indiana [Member]

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

Available-for-sale Securities

The following table presents the estimated fair value of investments in available-for-sale securities.

	September 30, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized		Estimated		Unrealized		Unrealized		Estimated
	Holding		Holding		Fair		Holding		Holding		Fair
(in millions)	Gains		Losses(b)		Value		Gains		Losses(b)		Value
Other Investments
Equity securities	$	23	$	—	$	67	$	28	$	—	$	71
Corporate debt securities	—		—		3		—		—		—
Municipal bonds	—		1		27		—		1		30
Total Other Investments(a)	$	23	$	1	$	97	$	28	$	1	$	101
Total Investments	$	23	$	1	$	97	$	28	$	1	$	101

(a)    These amounts are recorded in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

(b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.

(in millions)	September 30, 2015
Due in one year or less	$	2
Due after one through five years	16
Due after five through 10 years	8
Due after 10 years	4
Total	$	30