Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 2,011		$ 1,884
Gross Unrealized Holding Losses	42		47
Estimated Fair Value	5,747		5,551
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,973		1,852
Gross Unrealized Holding Losses	37		36
Estimated Fair Value	5,374		5,133
Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	74		110
Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,943		1,813
Gross Unrealized Holding Losses	28		10
Estimated Fair Value	3,825		3,579
Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	13		8
Gross Unrealized Holding Losses	3		6
Estimated Fair Value	493		400
Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5		2
Gross Unrealized Holding Losses	1		6
Estimated Fair Value	132		160
Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12		7
Gross Unrealized Holding Losses	4		12
Estimated Fair Value	713		730
Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains			22
Gross Unrealized Holding Losses	1		2
Estimated Fair Value	137		154
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	38	[1]	32	[1]
Gross Unrealized Holding Losses	5	[1]	11	[1]
Estimated Fair Value	373	[1]	418	[1]
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	16		21
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	32		29
Gross Unrealized Holding Losses
Estimated Fair Value	95		91
Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2		1
Gross Unrealized Holding Losses			1
Estimated Fair Value	68		99
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3		2
Gross Unrealized Holding Losses			2
Estimated Fair Value	82		79
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	16		17
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	5		8
Estimated Fair Value	96		111
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,058		1,004
Gross Unrealized Holding Losses	24		23
Estimated Fair Value	2,972		2,837
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,058		1,004
Gross Unrealized Holding Losses	23		22
Estimated Fair Value	2,969		2,834
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	39		42
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,046		974
Gross Unrealized Holding Losses	17		6
Estimated Fair Value	2,124		1,964
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7		5
Gross Unrealized Holding Losses	3		5
Estimated Fair Value	345		274
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses			2
Estimated Fair Value	22		54
Duke Energy Carolinas [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		3
Gross Unrealized Holding Losses	2		7
Estimated Fair Value	317		354
Duke Energy Carolinas [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains			22
Gross Unrealized Holding Losses	1		2
Estimated Fair Value	122		146
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				[1]
Gross Unrealized Holding Losses	1	[1]	1	[1]
Estimated Fair Value	3	[1]	3	[1]
Duke Energy Carolinas [Member] | Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses	1		1
Estimated Fair Value	3		3
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	918		849
Gross Unrealized Holding Losses	14		14
Estimated Fair Value	2,463		2,358
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	915		848
Gross Unrealized Holding Losses	14		14
Estimated Fair Value	2,405		2,299
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	35		68
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	897		839
Gross Unrealized Holding Losses	11		4
Estimated Fair Value	1,701		1,615
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6		3
Gross Unrealized Holding Losses			1
Estimated Fair Value	148		126
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		2
Gross Unrealized Holding Losses	1		4
Estimated Fair Value	110		106
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8		4
Gross Unrealized Holding Losses	2		5
Estimated Fair Value	396		376
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	15		8
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[1]	1	[1]
Gross Unrealized Holding Losses		[1]		[1]
Estimated Fair Value	58	[1]	59	[1]
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	15		20
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3		1
Gross Unrealized Holding Losses
Estimated Fair Value	43		39
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	588		544
Gross Unrealized Holding Losses	10		11
Estimated Fair Value	1,625		1,540
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	588		544
Gross Unrealized Holding Losses	10		11
Estimated Fair Value	1,623		1,538
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	28		48
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	574		535
Gross Unrealized Holding Losses	7		3
Estimated Fair Value	1,127		1,069
Duke Energy Progress [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		3
Gross Unrealized Holding Losses			1
Estimated Fair Value	95		80
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		2
Gross Unrealized Holding Losses	1		4
Estimated Fair Value	108		104
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6		4
Gross Unrealized Holding Losses	2		3
Estimated Fair Value	257		232
Duke Energy Progress [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	8		5
Duke Energy Progress [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains		[1]		[1]
Gross Unrealized Holding Losses		[1]		[1]
Estimated Fair Value	2	[1]	2	[1]
Duke Energy Progress [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	2		2
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	330		305
Gross Unrealized Holding Losses	4		3
Estimated Fair Value	825		803
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	327		304
Gross Unrealized Holding Losses	4		3
Estimated Fair Value	782		761
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	7		20
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	323		304
Gross Unrealized Holding Losses	4		1
Estimated Fair Value	574		546
Duke Energy Florida [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses
Estimated Fair Value	53		46
Duke Energy Florida [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	2		2
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses			2
Estimated Fair Value	139		144
Duke Energy Florida [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	7		3
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[1]	1	[1]
Gross Unrealized Holding Losses		[1]		[1]
Estimated Fair Value	43	[1]	42	[1]
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value			3
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3		1
Gross Unrealized Holding Losses
Estimated Fair Value	43		39
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	26		24
Gross Unrealized Holding Losses			1
Estimated Fair Value	99		94
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	26	[1]	24	[1]
Gross Unrealized Holding Losses		[1]	1	[1]
Estimated Fair Value	99	[1]	94	[1]
Duke Energy Indiana [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses
Estimated Fair Value	1		1
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	26		24
Gross Unrealized Holding Losses
Estimated Fair Value	68		65
Duke Energy Indiana [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains
Gross Unrealized Holding Losses			1
Estimated Fair Value	$ 30		$ 28

[1] These amounts are recorded in Other with Investments and Other Assets on the Condensed Consolidated Balance Sheets.