Other Income & Expenses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	$ 50		$ 53		$ 67
Foreign exchange gains (losses)	(5)	[1]	2	[1]	1	[1]
AFUDC equity	300		260		234
Deferred returns	24		10		15
Other	28		51		53
Total	567		547		589
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	11		10		23
AFUDC equity	154		168		174
Deferred returns	24		10		15
Other	(4)		(2)		0
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2		2		7
AFUDC equity	106		103		92
Contingent Value Obligation Unrealized Gain Loss			(59)
Other	22		6		10
Progress Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	1		1		3
AFUDC equity	69		71		64
Other	9		8		4
Progress Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	1		1		1
AFUDC equity	37		32		28
Other	1		(3)		3
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	10		14		18
AFUDC equity	6		5		4
Other	(3)		0		3
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	7		14		14
AFUDC equity	84		88		56
Other	$ (1)		$ (5)		$ 0

[1] Primarily relates to International Energy's remeasurement of certain cash and debt balances into the functional currency.