Employee Benefit Plans (Reconciliation of Assets Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended					12 Months Ended						12 Months Ended
	Dec. 31, 2012 Master Trust [Member]	Dec. 31, 2011 Master Trust [Member]	Dec. 31, 2011 Progress Energy [Member]	Dec. 31, 2010 Progress Energy [Member]	Dec. 31, 2012 Progress Energy [Member]	Dec. 31, 2012 Progress Energy [Member] Master Trust [Member]	Dec. 31, 2011 Progress Energy [Member] Master Trust [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member]	Dec. 31, 2011 Progress Energy Carolinas [Member]	Dec. 31, 2010 Progress Energy Carolinas [Member]	Dec. 31, 2009 Progress Energy Carolinas [Member]	Dec. 31, 2010 Progress Energy Florida [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Dec. 31, 2011 Duke Energy Ohio [Member]	Dec. 31, 2010 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2011 Duke Energy Indiana [Member]	Dec. 31, 2010 Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	$ 322	$ 185	$ (36)	$ (39)	$ (38)	$ 311	$ 160	$ (38)	$ (24)	$ (36)	$ (27)	$ (12)	$ (3)	$ 13	$ 7	$ 4	$ 4	$ 4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issuances, Settlements															8			(15)
Purchases	21	156				13	107										8
Sales	(4)	(29)				(14)	(13)									(22)
Transfers in and/or out of level 3			33	47		(41)						29
Total losses, (realized and unrealized) and other	13	10				19	57						4	4	(8)
Ending balance	$ 352	$ 322	$ (24)	$ (36)	$ (38)	$ 288	$ 311	$ (38)	$ (24)	$ (36)	$ (27)	$ 0	$ (6)	$ (3)	$ 13	$ 10	$ 4	$ 4