Investments In Debt And Equity Securities (Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 1,216		$ 483
Gross Unrealized Holding Losses	30		42
Estimated Fair Value	4,932		2,549
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,199		473
Gross Unrealized Holding Losses	23		22
Estimated Fair Value	4,263		2,060
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	17	[1]	10	[1]
Gross Unrealized Holding Losses	7	[1]	20	[1]
Estimated Fair Value	669	[1]	489	[1]
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	632		473
Gross Unrealized Holding Losses	9		25
Estimated Fair Value	2,364		2,072
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	632		473
Gross Unrealized Holding Losses	8		22
Estimated Fair Value	2,361		2,060
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	[2]	3	[2]
Estimated Fair Value	3	[2]	12	[2]
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	570		444
Gross Unrealized Holding Losses	15		31
Estimated Fair Value	1,959		1,650
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	567		444
Gross Unrealized Holding Losses	15		31
Estimated Fair Value	1,902		1,630
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[1]
Estimated Fair Value	57	[1]	20	[1]
Progress Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	363		287
Gross Unrealized Holding Losses	11		20
Estimated Fair Value	1,278		1,107
Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	363		287
Gross Unrealized Holding Losses	11		20
Estimated Fair Value	1,275		1,101
Progress Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	3	[1]	6	[1]
Progress Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	207		157
Gross Unrealized Holding Losses	4		11
Estimated Fair Value	668		530
Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	204		157
Gross Unrealized Holding Losses	4		11
Estimated Fair Value	627		529
Progress Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[3]
Estimated Fair Value	41	[3]	1	[3]
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10		6
Gross Unrealized Holding Losses			1
Estimated Fair Value	78		74
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10	[1]	6	[1]
Gross Unrealized Holding Losses			1	[1]
Estimated Fair Value	78	[1]	74	[1]
Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	105		63
Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	17
Cash and Cash Equivalents [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	40		63
Cash and Cash Equivalents [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	65		56
Cash and Cash Equivalents [Member] | Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	17		20
Cash and Cash Equivalents [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	55		49
Cash and Cash Equivalents [Member] | Progress Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	3		6
Cash and Cash Equivalents [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	10		7
Cash and Cash Equivalents [Member] | Progress Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1		1
Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,132		443
Gross Unrealized Holding Losses	19		16
Estimated Fair Value	2,837		1,337
Equity Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10		5
Gross Unrealized Holding Losses			2
Estimated Fair Value	63		60
Equity Securities [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	600		443
Gross Unrealized Holding Losses	5		16
Estimated Fair Value	1,592		1,337
Equity Securities [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	532		412
Gross Unrealized Holding Losses	14		29
Estimated Fair Value	1,245		1,062
Equity Securities [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	337		262
Gross Unrealized Holding Losses	11		20
Estimated Fair Value	811		690
Equity Securities [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	194		150
Gross Unrealized Holding Losses	4		9
Estimated Fair Value	434		372
Equity Securities [Member] | Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9		5
Gross Unrealized Holding Losses			1
Estimated Fair Value	50		46
Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	21		8
Gross Unrealized Holding Losses	1		2
Estimated Fair Value	338		205
Corporate Debt Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2		1
Gross Unrealized Holding Losses			1
Estimated Fair Value	381		241
Corporate Debt Securities [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	11		8
Gross Unrealized Holding Losses	1		2
Estimated Fair Value	250		205
Corporate Debt Securities [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9		6
Estimated Fair Value	89		86
Corporate Debt Securities [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8		5
Estimated Fair Value	78		69
Corporate Debt Securities [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		1
Estimated Fair Value	11		17
Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12		2
Gross Unrealized Holding Losses	1
Estimated Fair Value	194		51
Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		1
Gross Unrealized Holding Losses	1
Estimated Fair Value	70		28
Municipal Bonds [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2		2
Estimated Fair Value	40		51
Municipal Bonds [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	11		7
Gross Unrealized Holding Losses	1		2
Estimated Fair Value	154		127
Municipal Bonds [Member] | Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3
Estimated Fair Value	40
Municipal Bonds [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4		3
Estimated Fair Value	80		55
Municipal Bonds [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7		4
Gross Unrealized Holding Losses			2
Estimated Fair Value	74		72
Municipal Bonds [Member] | Progress Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3
Estimated Fair Value	40
Municipal Bonds [Member] | Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		1
Estimated Fair Value	28		28
US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	24		16
Gross Unrealized Holding Losses	1
Estimated Fair Value	625		306
US Treasury and Government [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains			1
Estimated Fair Value	23		21
US Treasury and Government [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10		16
Estimated Fair Value	304		306
US Treasury and Government [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	14		18
Estimated Fair Value	321		268
US Treasury and Government [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	13		16
Estimated Fair Value	241		225
US Treasury and Government [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		2
Estimated Fair Value	80		43
Auction Rate Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	6		17
Estimated Fair Value	29		71
Auction Rate Securities [Member] | Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1		3
Estimated Fair Value	3		12
Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10		4
Gross Unrealized Holding Losses	1		4
Estimated Fair Value	164		98
Other Debt Obligations [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		2
Estimated Fair Value	86		68
Other Debt Obligations [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9		4
Gross Unrealized Holding Losses	2		4
Estimated Fair Value	135		98
Other Debt Obligations [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		1
Estimated Fair Value	28		31
Other Debt Obligations [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1		1
Estimated Fair Value	10		13
Other Debt Obligations [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1
Estimated Fair Value	$ 18		$ 18

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

[2] These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets.

[3] These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance sheets.