Commitments and Contingencies (Schedule of Environmental Loss Contingencies)(Details) (USD $) In Millions, unless otherwise specified	6 Months Ended							6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Minimum [Member]	Jun. 30, 2013 Maximum [Member]	Jun. 30, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2013 Duke Energy Carolinas [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2013 Duke Energy Carolinas [Member] Minimum [Member]	Jun. 30, 2013 Duke Energy Carolinas [Member] Maximum [Member]	Jun. 30, 2013 Duke Energy Ohio [Member]	Jun. 30, 2012 Duke Energy Ohio [Member]	Jun. 30, 2013 Duke Energy Ohio [Member] Minimum [Member]	Jun. 30, 2013 Duke Energy Ohio [Member] Maximum [Member]	Jun. 30, 2013 Duke Energy Indiana [Member]	Jun. 30, 2012 Duke Energy Indiana [Member]	Jun. 30, 2013 Duke Energy Indiana [Member] Minimum [Member]	Jun. 30, 2013 Duke Energy Indiana [Member] Maximum [Member]	Jun. 30, 2013 Progress Energy [Member]	Jun. 30, 2012 Progress Energy [Member]	Jun. 30, 2013 Progress Energy [Member] Minimum [Member]	Jun. 30, 2013 Progress Energy [Member] Maximum [Member]	Jun. 30, 2013 Duke Energy Progress [Member]	Jun. 30, 2012 Duke Energy Progress [Member]	Jun. 30, 2013 Duke Energy Progress [Member] Minimum [Member]	Jun. 30, 2013 Duke Energy Progress [Member] Maximum [Member]	Jun. 30, 2013 Duke Energy Florida [Member]	Jun. 30, 2012 Duke Energy Florida [Member]	Jun. 30, 2013 Duke Energy Florida [Member] Minimum [Member]	Jun. 30, 2013 Duke Energy Florida [Member] Maximum [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 75	$ 61			$ 12	$ 12	$ 12			$ 15	$ 28			$ 8	$ 9			$ 33	$ 23			$ 14	$ 11			$ 19	$ 12
Provision/adjustments	4	7			1					(1)	4			1	1			4	17			1	4			3	13
Cash reductions	(12)	(14)								(6)	(10)			(2)	(1)			(3)	(6)			(1)	(1)			(2)	(5)
Ending balance	67	54			13	12	12			8	22			7	9			34	34			14	14			20	20
Estimated cost of complying with EPA Mercury and Air Toxics Standards			$ 650	$ 800				$ 65	$ 85			$ 40	$ 85			$ 540	$ 600			$ 7	$ 30			$ 5	$ 10			$ 2	$ 20