Investments In Debt And Equity Securities (Unrealized Losses Of Available-For-Sale Debt And Equity Securities In A Continuous Loss Position) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 484	$ 584
Unrealized Loss Position greater than 12 months	12	25
Unrealized Loss Position less than 12 months	18	17
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	399	289
Unrealized Loss Position greater than 12 months	5	6
Unrealized Loss Position less than 12 months	18	16
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	85	295
Unrealized Loss Position greater than 12 months	7	19
Unrealized Loss Position less than 12 months		1
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	210	301
Unrealized Loss Position greater than 12 months	1	9
Unrealized Loss Position less than 12 months	8	16
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	207	289
Unrealized Loss Position greater than 12 months		6
Unrealized Loss Position less than 12 months	8	16
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3	12
Unrealized Loss Position greater than 12 months	1	3
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	198	136
Unrealized Loss Position greater than 12 months	4	12
Unrealized Loss Position less than 12 months	11	19
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	191	136
Unrealized Loss Position greater than 12 months	4	12
Unrealized Loss Position less than 12 months	11	19
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7
Progress Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	133	98
Unrealized Loss Position greater than 12 months	2	10
Unrealized Loss Position less than 12 months	9	10
Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	133	98
Unrealized Loss Position greater than 12 months	2	10
Unrealized Loss Position less than 12 months	9	10
Progress Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	65	38
Unrealized Loss Position greater than 12 months	3	2
Unrealized Loss Position less than 12 months	1	9
Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	58	38
Unrealized Loss Position greater than 12 months	3	2
Unrealized Loss Position less than 12 months	1	9
Progress Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	12	11
Unrealized Loss Position less than 12 months		1
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	12	11
Unrealized Loss Position less than 12 months		1
Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	155	111
Unrealized Loss Position greater than 12 months	4	4
Unrealized Loss Position less than 12 months	15	12
Equity Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	4	12
Unrealized Loss Position greater than 12 months		1
Unrealized Loss Position less than 12 months		1
Equity Securities [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	71	111
Unrealized Loss Position greater than 12 months		4
Unrealized Loss Position less than 12 months	5	12
Equity Securities [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	83	112
Unrealized Loss Position greater than 12 months	4	10
Unrealized Loss Position less than 12 months	10	19
Equity Securities [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	59	69
Unrealized Loss Position greater than 12 months	2	10
Unrealized Loss Position less than 12 months	9	10
Equity Securities [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	24	43
Unrealized Loss Position greater than 12 months	2
Unrealized Loss Position less than 12 months	1	9
Equity Securities [Member] | Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value		8
Unrealized Loss Position less than 12 months		1
Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	42	57
Unrealized Loss Position greater than 12 months		1
Unrealized Loss Position less than 12 months	1	1
Corporate Debt Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7	201
Unrealized Loss Position greater than 12 months		1
Corporate Debt Securities [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	35	57
Unrealized Loss Position greater than 12 months		1
Unrealized Loss Position less than 12 months	1	1
Corporate Debt Securities [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	6	20
Corporate Debt Securities [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	6	10
Corporate Debt Securities [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value		10
Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	29
Unrealized Loss Position greater than 12 months	1
Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	18	3
Unrealized Loss Position greater than 12 months	1
Municipal Bonds [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3
Municipal Bonds [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	26	21
Unrealized Loss Position greater than 12 months		2
Municipal Bonds [Member] | Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7
Municipal Bonds [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	18	8
Municipal Bonds [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	8	13
Unrealized Loss Position greater than 12 months	1	2
Municipal Bonds [Member] | Progress Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7
Municipal Bonds [Member] | Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	12	3
US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	135	8
Unrealized Loss Position less than 12 months	1
US Treasury and Government [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	6
US Treasury and Government [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	62	8
US Treasury and Government [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	74	(23)
Unrealized Loss Position less than 12 months	1
US Treasury and Government [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	49	9
US Treasury and Government [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	25	(32)
Auction Rate Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	29	71
Unrealized Loss Position greater than 12 months	6	17
Auction Rate Securities [Member] | Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3	12
Unrealized Loss Position greater than 12 months	1	3
Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	38	113
Unrealized Loss Position greater than 12 months		1
Unrealized Loss Position less than 12 months	1	3
Other Debt Obligations [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	21	8
Other Debt Obligations [Member] | Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	36	113
Unrealized Loss Position greater than 12 months		1
Unrealized Loss Position less than 12 months	2	3
Other Debt Obligations [Member] | Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2	6
Other Debt Obligations [Member] | Progress Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1	2
Other Debt Obligations [Member] | Progress Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 1	$ 4