Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2017

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2			Level 3			Not categorized
Nuclear decommissioning trust fund equity securities	$	4,284		$	4,207	$	—		$	—		$	77
Nuclear decommissioning trust fund debt securities	2,107			602		1,505			—			—
Other trading and available-for-sale equity securities	110			110		—			—			—
Other trading and available-for-sale debt securities	248			61		182			5			—
Derivative assets	83			2		71			10			—
Total assets	6,832			4,982		1,758			15			77
Derivative liabilities	(216		)	—		(71		)	(145		)	—
Net assets (liabilities)	$	6,616		$	4,982	$	1,687		$	(130	)	$	77

	December 31, 2016
(in millions)	Total Fair Value			Level 1			Level 2			Level 3			Not categorized
Nuclear decommissioning trust fund equity securities	$	4,106		$	4,029		$	—		$	—		$	77
Nuclear decommissioning trust fund debt securities	2,078			632			1,446			—			—
Other trading and available-for-sale equity securities	104			104			—			—			—
Other trading and available-for-sale debt securities	266			75			186			5			—
Derivative assets	162			5			136			21			—
Total assets	6,716			4,845			1,768			26			77
Derivative liabilities	(252		)	(2		)	(63		)	(187		)	—
Net assets (liabilities)	$	6,464		$	4,843		$	1,705		$	(161	)	$	77

Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs

The following tables provide reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Amounts included in earnings for derivatives are primarily included in Operating Revenues.

	Three Months Ended March 31, 2017
(in millions)	Investments		Derivatives (net)			Total
Balance at beginning of period	$	5	$	(166	)	$	(161	)
Purchases, sales, issuances and settlements:
Settlements	—		(9		)	(9		)
Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	—		40			40
Balance at end of period	$	5	$	(135	)	$	(130	)

	Three Months Ended March 31, 2016
(in millions)	Investments			Derivatives (net)			Total
Balance at beginning of period	$	5		$	10		$	15
Purchases, sales, issuances and settlements:
Sales	(1		)	—			(1		)
Settlements	—			(7		)	(7		)
Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	—			(1		)	(1		)
Balance at end of period	$	4		$	2		$	6

Quantitative Information Table - Level 3

The following table includes quantitative information about the Duke Energy Registrants' derivatives classified as Level 3.

	March 31, 2017
	Fair Value
Investment Type	(in millions)			Valuation Technique	Unobservable Input	Range
Duke Energy Ohio
Financial Transmission Rights (FTRs)	$	1		RTO auction pricing	FTR price – per megawatt-hour (MWh)	$	0.23		-	$	2.02
Duke Energy Indiana
FTRs	9			RTO auction pricing	FTR price – per MWh	(1.08		)	-	5.33
Piedmont
Natural gas contracts	(145		)	Discounted cash flow	Forward natural gas curves – price per million British thermal unit (MMBtu)	2.08			-	3.57
Duke Energy
Total Level 3 derivatives	$	(135	)

	December 31, 2016
	Fair Value
Investment Type	(in millions)			Valuation Technique	Unobservable Input	Range
Duke Energy Ohio
FTRs	$	5		RTO auction pricing	FTR price – per MWh	$	0.77		-	$	3.52
Duke Energy Indiana
FTRs	16			RTO auction pricing	FTR price – per MWh	(0.83		)	-	9.32
Piedmont
Natural gas contracts	(187		)	Discounted cash flow	Forward natural gas curves – price per MMBtu	2.31			-	4.18
Duke Energy
Total Level 3 derivatives	$	(166	)

Schedule Of Long Term Debt Fair Value

The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements.

	March 31, 2017				December 31, 2016
(in millions)	Book Value		Fair Value		Book Value		Fair Value
Duke Energy	$	48,998	$	50,480	$	47,895	$	49,161
Duke Energy Carolinas	9,491		10,405		9,603		10,494
Progress Energy	18,148		19,742		17,541		19,107
Duke Energy Progress	6,761		7,103		7,011		7,357
Duke Energy Florida	6,981		7,596		6,125		6,728
Duke Energy Ohio	1,977		2,122		1,884		2,020
Duke Energy Indiana	3,784		4,292		3,786		4,260
Piedmont	1,821		1,954		1,821		1,933

Duke Energy Carolinas [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2			Level 3		Not categorized
Nuclear decommissioning trust fund equity securities	$	2,366		$	2,289	$	—		$	—	$	77
Nuclear decommissioning trust fund debt securities	1,026			146		880			—		—
Other available-for-sale debt securities	3			—		—			3		—
Derivative assets	17			—		17			—		—
Total assets	3,412			2,435		897			3		77
Derivative liabilities	(14		)	—		(14		)	—		—
Net assets	$	3,398		$	2,435	$	883		$	3	$	77

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 2			Level 3		Not categorized
Nuclear decommissioning trust fund equity securities	$	2,245		$	2,168	$	—		$	—	$	77
Nuclear decommissioning trust fund debt securities	1,013			178		835			—		—
Other available-for-sale debt securities	3			—		—			3		—
Derivative assets	33			—		33			—		—
Total assets	3,294			2,346		868			3		77
Derivative liabilities	(16		)	—		(16		)	—		—
Net assets	$	3,278		$	2,346	$	852		$	3	$	77

Progress Energy [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	1,918		$	1,918	$	—
Nuclear decommissioning trust fund debt securities	1,081			456		625
Other available-for-sale debt securities	58			12		46
Derivative assets	34			—		34
Total assets	3,091			2,386		705
Derivative liabilities	(34		)	—		(34		)
Net assets	$	3,057		$	2,386	$	671

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	1,861		$	1,861	$	—
Nuclear decommissioning trust fund debt securities	1,065			454		611
Other available-for-sale debt securities	65			21		44
Derivative assets	85			—		85
Total assets	3,076			2,336		740
Derivative liabilities	(25		)	—		(25		)
Net assets	$	3,051		$	2,336	$	715

Duke Energy Progress [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	1,541		$	1,541	$	—
Nuclear decommissioning trust fund debt securities and other	733			221		512
Other available-for-sale debt securities and other	1			1		—
Derivative assets	20			—		20
Total assets	2,295			1,763		532
Derivative liabilities	(10		)	—		(10		)
Net assets	$	2,285		$	1,763	$	522

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	1,505		$	1,505	$	—
Nuclear decommissioning trust fund debt securities and other	708			207		501
Other available-for-sale debt securities and other	1			1		—
Derivative assets	46			—		46
Total assets	2,260			1,713		547
Derivative liabilities	(7		)	—		(7		)
Net assets	$	2,253		$	1,713	$	540

Duke Energy Florida [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	377		$	377	$	—
Nuclear decommissioning trust fund debt securities and other	348			235		113
Other available-for-sale debt securities and other	47			1		46
Derivative assets	14			—		14
Total assets	786			613		173
Derivative liabilities	(19		)	—		(19		)
Net assets	$	767		$	613	$	154

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 2
Nuclear decommissioning trust fund equity securities	$	356		$	356	$	—
Nuclear decommissioning trust fund debt securities and other	357			247		110
Other available-for-sale debt securities and other	48			4		44
Derivative assets	39			—		39
Total assets	800			607		193
Derivative liabilities	(12		)	—		(12		)
Net assets	$	788		$	607	$	181

Duke Energy Ohio [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which are disclosed in Note 9.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 2			Level 3
Derivative assets	$	1		$	—	$	—		$	1
Derivative liabilities	(5		)	—		(5		)	—
Net (liabilities) assets	$	(4	)	$	—	$	(5	)	$	1

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 2			Level 3
Derivative assets	$	5		$	—	$	—		$	5
Derivative liabilities	(6		)	—		(6		)	—
Net (liabilities) assets	$	(1	)	$	—	$	(6	)	$	5

Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs

The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.

	Derivatives (net)
	Three Months Ended March 31,
(in millions)	2017			2016
Balance at beginning of period	$	5		$	3
Purchases, sales, issuances and settlements:
Settlements	(1		)	(2		)
Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	(3		)	(1		)
Balance at end of period	$	1		$	—

Duke Energy Indiana [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type.

	March 31, 2017
(in millions)	Total Fair Value		Level 1		Level 2		Level 3
Other available-for-sale equity securities	$	84	$	84	$	—	$	—
Other available-for-sale debt securities and other	31		—		31		—
Derivative assets	9		—		—		9
Net assets	$	124	$	84	$	31	$	9

	December 31, 2016
(in millions)	Total Fair Value			Level 1			Level 2		Level 3
Other available-for-sale equity securities	$	79		$	79		$	—	$	—
Other available-for-sale debt securities and other	31			—			31		—
Derivative assets	16			—			—		16
Total assets	126			79			31		16
Derivative liabilities	(2		)	(2		)	—		—
Net assets	$	124		$	77		$	31	$	16

Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs

The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.

	Derivatives (net)
	Three Months Ended March 31,
(in millions)	2017			2016
Balance at beginning of period	$	16		$	7
Purchases, sales, issuances and settlements:
Settlements	(7		)	(5		)
Balance at end of period	$	9		$	2

Piedmont Natural Gas [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurement Amounts For Assets And Liabilities

The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. See Note 10 for additional information related to investments.

	March 31, 2017
(in millions)	Total Fair Value			Level 1		Level 3
Other trading equity securities	4			4		—
Other trading debt securities	1			1		—
Derivative assets	2			2		—
Total assets	7			7		—
Derivative liabilities	(145		)	—		(145		)
Net (liabilities) assets	$	(138	)	$	7	$	(145	)

	December 31, 2016
(in millions)	Total Fair Value			Level 1		Level 3
Other trading equity securities	$	4		$	4	$	—
Other trading debt securities	1			1		—
Derivative assets	3			3		—
Total assets	8			8		—
Derivative liabilities	(187		)	—		(187		)
Net (liabilities) assets	$	(179	)	$	8	$	(187	)

Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs

The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.

	Derivatives (net)
	Three Months Ended March 31,
(in millions)	2017			2016
Balance at beginning of period	$	(187	)	$	(149	)
Total gains and settlements	42			23
Balance at end of period	$	(145	)	$	(126	)