Investments in Debt and Equity Securities (Tables)

6 Months Ended

Jun. 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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
NDTF
Cash and cash equivalents	$	1	$	—	$	120	$	—	$	—	$	136
Equity securities	1,890		31		3,654		1,926		29		3,650
Corporate debt securities	8		7		510		14		2		454
Municipal bonds	4		4		226		5		—		184
U.S. government bonds	14		3		838		19		2		978
Other debt securities	1		3		188		1		2		147
Total NDTF(c)	$	1,918	$	48	$	5,536	$	1,965	$	35	$	5,549
Other Investments
Cash and cash equivalents	$	—	$	—	$	30	$	—	$	—	$	15
Equity securities	35		—		98		34		—		96
Corporate debt securities	1		2		94		1		1		58
Municipal bonds	2		1		70		3		1		76
U.S. government bonds	—		—		55		—		—		27
Other debt securities	—		1		71		1		1		80
Total Other Investments(a)	$	38	$	4	$	418	$	39	$	3	$	352
Total Investments	$	1,956	$	52	$	5,954	$	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 represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.

(c) The decrease in the estimated fair value of the NDTF for the six months ended June 30, 2015, is primarily due to reimbursement 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)	June 30, 2015
Due in one year or less	$	86
Due after one through five years	642
Due after five through 10 years	500
Due after 10 years	824
Total	$	2,052

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 June 30,				Six Months Ended June 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	28	$	31	$	130	$	62
Realized losses	17		2		31		6

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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	43	$	—	$	—	$	51
Equity securities	1,061		19		2,132		1,102		17		2,162
Corporate debt securities	4		6		352		8		2		316
Municipal bonds	1		2		90		1		—		62
U.S. government bonds	4		2		329		7		1		308
Other debt securities	1		3		153		1		2		133
Total NDTF	$	1,071	$	32	$	3,099	$	1,119	$	22	$	3,032
Other Investments
Other debt securities	$	—	$	1	$	3	$	—	$	1	$	3
Total Other Investments(a)	$	—	$	1	$	3	$	—	$	1	$	3
Total Investments	$	1,071	$	33	$	3,102	$	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)	June 30, 2015
Due in one year or less	$	10
Due after one through five years	197
Due after five through 10 years	275
Due after 10 years	445
Total	$	927

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 June 30,				Six Months Ended June 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	17	$	29	$	107	$	52
Realized losses	11		1		23		2

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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
NDTF
Cash and cash equivalents	$	1	$	—	$	77	$	—	$	—	$	85
Equity securities	829		12		1,522		824		12		1,488
Corporate debt securities	4		1		158		6		—		138
Municipal bonds	3		2		136		4		—		122
U.S. government bonds	10		1		509		12		1		670
Other debt securities	—		—		35		—		—		14
Total NDTF(c)	$	847	$	16	$	2,437	$	846	$	13	$	2,517
Other Investments
Cash and cash equivalents	$	—	$	—	$	21	$	—	$	—	$	15
Municipal bonds	2		—		40		3		—		43
Total Other Investments(a)	$	2	$	—	$	61	$	3	$	—	$	58
Total Investments	$	849	$	16	$	2,498	$	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) The decrease in the estimated fair value of the NDTF for the six months ended June 30, 2015, is primarily due to reimbursement 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)	June 30, 2015
Due in one year or less	$	55
Due after one through five years	345
Due after five through 10 years	156
Due after 10 years	322
Total	$	878

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 June 30,				Six Months Ended June 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	9	$	2	$	21	$	9
Realized losses	5		1		6		3

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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
NDTF
Cash and cash equivalents	$	1	$	—	$	47	$	—	$	—	$	50
Equity securities	617		10		1,198		612		10		1,171
Corporate debt securities	3		1		110		5		—		97
Municipal bonds	3		2		134		4		—		120
U.S. government bonds	7		1		228		9		1		265
Other debt securities	—		—		21		—		—		8
Total NDTF	$	631	$	14	$	1,738	$	630	$	11	$	1,711
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	—
Total Other Investments(a)	$	—	$	—	$	1	$	—	$	—	$	—
Total Investments	$	631	$	14	$	1,739	$	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.

Investments Classified by Contractual Maturity Date

The table below summarizes the maturity date for debt securities.

(in millions)	June 30, 2015
Due in one year or less	$	12
Due after one through five years	142
Due after five through 10 years	106
Due after 10 years	233
Total	$	493

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 June 30,				Six Months Ended June 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	8	$	1	$	17	$	7
Realized losses	4		—		5		2

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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	30	$	—	$	—	$	35
Equity securities	212		2		324		212		2		317
Corporate debt securities	1		—		48		1		—		41
Municipal bonds	—		—		2		—		—		2
U.S. government bonds	3		—		281		3		—		405
Other debt securities	—		—		14		—		—		6
Total NDTF(c)	$	216	$	2	$	699	$	216	$	2	$	806
Other Investments
Cash and cash equivalents	$	—	$	—	$	9	$	—	$	—	$	1
Municipal bonds	2		—		40		3		—		43
Total Other Investments(a)	$	2	$	—	$	49	$	3	$	—	$	44
Total Investments	$	218	$	2	$	748	$	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 decrease in the estimated fair value of the NDTF for the six months ended June 30, 2015, is primarily due to reimbursement 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)	June 30, 2015
Due in one year or less	$	43
Due after one through five years	203
Due after five through 10 years	50
Due after 10 years	89
Total	$	385

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 June 30,				Six Months Ended June 30,
(in millions)	2015		2014		2015		2014
Realized gains	$	1	$	1	$	4	$	2
Realized losses	1		—		1		1

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.

	June 30, 2015						December 31, 2014
(in millions)	Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses(b)		Estimated Fair Value
Other Investments
Equity securities	$	29	$	—	$	73	$	28	$	—	$	71
Corporate debt securities	—		—		3		—		—		—
Municipal bonds	—		1		27		—		1		30
Total Other Investments(a)	$	29	$	1	$	103	$	28	$	1	$	101
Total Investments	$	29	$	1	$	103	$	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)	June 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