Investments in Debt and Equity Securities (Tables)

12 Months Ended

Dec. 31, 2015

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	179	$	—	$	—	$	136
Equity securities	1,823		58		3,590		1,926		29		3,650
Corporate debt securities	7		8		432		14		2		454
Municipal bonds	5		1		185		5		—		184
U.S. government bonds	11		5		1,254		19		2		978
Other debt securities	—		4		177		1		2		147
Total NDTF(c)	$	1,846	$	76	$	5,817	$	1,965	$	35	$	5,549
Other Investments
Cash and cash equivalents	$	—	$	—	$	29	$	—	$	—	$	15
Equity securities	32		1		95		34		—		96
Corporate debt securities	1		3		92		1		1		58
Municipal bonds	3		1		74		3		1		76
U.S. government bonds	—		—		45		—		—		27
Other debt securities	—		2		62		1		1		80
Total Other Investments(a)	$	36	$	7	$	397	$	39	$	3	$	352
Total Investments	$	1,882	$	83	$	6,214	$	2,004	$	38	$	5,901

(a)     These amounts are recorded in Other within Investments and Other Assets on the 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) The increase in estimated fair value of the NDTF as of December 31, 2015, is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This 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. Refer to Note 2 for further information.

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	120
Due after one through five years	775
Due after five through 10 years	598
Due after 10 years	828
Total	2,321

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.

	Years Ended December 31,
(in millions)	2015		2014		2013
Realized gains	$	193	$	271	$	209
Realized losses	98		105		65

Duke Energy Carolinas [Member]

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	34	$	—	$	—	$	51
Equity securities	1,021		27		2,094		1,102		17		2,162
Corporate debt securities	3		5		292		8		2		316
Municipal bonds	1		—		33		1		—		62
U.S. government bonds	3		3		438		7		1		308
Other debt securities	—		4		147		1		2		133
Total NDTF	$	1,028	$	39	$	3,038	$	1,119	$	22	$	3,032
Other Investments
Other debt securities	$	—	$	1	$	3	$	—	$	1	$	3
Total Other Investments(a)	$	—	$	1	$	3	$	—	$	1	$	3
Total Investments	$	1,028	$	40	$	3,041	$	1,119	$	23	$	3,035

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

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	$	13
Due after one through five years	187
Due after five through 10 years	275
Due after 10 years	438
Total	$	913

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.

	Years Ended December 31,
(in millions)	2015		2014		2013
Realized gains	$	158	$	109	$	115
Realized losses	83		93		12

Progress Energy [Member]

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	145	$	—	$	—	$	85
Equity securities	802		31		1,496		824		12		1,488
Corporate debt securities	4		3		140		6		—		138
Municipal bonds	4		1		152		4		—		122
U.S. government bonds	8		2		816		12		1		670
Other debt securities	—		—		30		—		—		14
Total NDTF(c)	$	818	$	37	$	2,779	$	846	$	13	$	2,517
Other Investments
Cash and cash equivalents	$	—	$	—	$	18	$	—	$	—	$	15
Municipal bonds	3		—		45		3		—		43
Total Other Investments(a)	$	3	$	—	$	63	$	3	$	—	$	58
Total Investments	$	821	$	37	$	2,842	$	849	$	13	$	2,575

(a)     These amounts are recorded in Other within Investments and Other Assets on the 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) The increase in estimated fair value of the NDTF as of December 31, 2015, is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This 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. Refer to Note 2 for further information.

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	$	94
Due after one through five years	496
Due after five through 10 years	254
Due after 10 years	339
Total	$	1,183

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.

	Years Ended December 31,
(in millions)	2015		2014		2013
Realized gains	$	33	$	157	$	90
Realized losses	13		11		46

Duke Energy Progress [Member]

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	110	$	—	$	—	$	50
Equity securities	596		25		1,178		612		10		1,171
Corporate debt securities	3		2		96		5		—		97
Municipal bonds	4		1		150		4		—		120
U.S. government bonds	6		2		486		9		1		265
Other debt securities	—		—		18		—		—		8
Total NDTF(c)	$	609	$	30	$	2,038	$	630	$	11	$	1,711
Other Investments
Cash and cash equivalents	$	—	$	—	$	1	$	—	$	—	$	—
Total Other Investments(a)	$	—	$	—	$	1	$	—	$	—	$	—
Total Investments	$	609	$	30	$	2,039	$	630	$	11	$	1,711

(a)    These amounts are recorded in Other with Investments and Other Assets on the 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 December 31, 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.

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	$	15
Due after one through five years	285
Due after five through 10 years	206
Due after 10 years	244
Total	$	750

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.

	Years Ended December 31,
(in millions)	2015		2014		2013
Realized gains	$	26	$	19	$	58
Realized losses	11		5		26

Duke Energy Florida [Member]

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
NDTF
Cash and cash equivalents	$	—	$	—	$	35	$	—	$	—	$	35
Equity securities	206		6		318		212		2		317
Corporate debt securities	1		1		44		1		—		41
Municipal bonds	—		—		2		—		—		2
U.S. government bonds	2		—		330		3		—		405
Other debt securities	—		—		12		—		—		6
Total NDTF(c)	$	209	$	7	$	741	$	216	$	2	$	806
Other Investments
Cash and cash equivalents	$	—	$	—	$	6	$	—	$	—	$	1
Municipal bonds	3		—		45		3		—		43
Total Other Investments(a)	$	3	$	—	$	51	$	3	$	—	$	44
Total Investments	$	212	$	7	$	792	$	219	$	2	$	850

(a)    These amounts are recorded in Other with Investments and Other Assets on the 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 estimated fair value of the NDTF as of December 31, 2015, is primarily due to reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant, partially offset by the NDTF asset acquired in a settlement with FMJO. Refer to Note 2 for further information.

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	$	79
Due after one through five years	211
Due after five through 10 years	48
Due after 10 years	95
Total	$	433

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.

	Years Ended December 31,
(in millions)	2015		2014		2013
Realized gains	$	7	$	138	$	32
Realized losses	2		5		20

Duke Energy Indiana [Member]

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

Available-For-Sale Investments

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

	December 31, 2015						December 31, 2014
	Gross		Gross				Gross		Gross
	Unrealized		Unrealized				Unrealized		Unrealized
	Holding		Holding		Estimated		Holding		Holding		Estimated
(in millions)	Gains		Losses(b)		Fair Value		Gains		Losses(b)		Fair Value
Other Investments
Cash and cash equivalents	$	—	$	—	$	2	$	—	$	—	$	—
Equity securities	27		—		71		28		—		71
Corporate debt securities	—		—		2		—		—		—
Municipal bonds	—		1		26		—		1		30
Total Other Investments(a)	$	27	$	1	$	101	$	28	$	1	$	101
Total Investments	$	27	$	1	$	101	$	28	$	1	$	101

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

Schedule of Maturity Dates for Debt Securities

The table below summarizes the maturity date for debt securities.

(in millions)	December 31, 2015
Due in one year or less	$	2
Due after one through five years	14
Due after five through 10 years	9
Due after 10 years	3
Total	$	28