Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Asset Retirement Obligation [Line Items]
Balance as of January 1	$ 1,936	$ 1,816
Acquisitions	3,062
Accretion expense	(173)	(111)
Liabilities settled	15	3
Revisions in estimates of cash flows	(4)	1
Liabilities incurred in the current year	24	11
Balance as of December 31	5,176	1,936
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	1,846	1,728
Accretion expense	(118)	(105)
Liabilities settled	3	1
Revisions in estimates of cash flows	(2)	9
Liabilities incurred in the current year	0	5
Balance as of December 31	1,959	1,846
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	1,265	1,200
Accretion expense	(86)	(67)
Liabilities settled	2	0
Revisions in estimates of cash flows	234	(2)
Liabilities incurred in the current year	837	0
Balance as of December 31	2,420	1,265
Progress Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	896	849
Accretion expense	(64)	(49)
Liabilities settled	2	0
Revisions in estimates of cash flows	0	(2)
Liabilities incurred in the current year	698	0
Balance as of December 31	1,656	896
Progress Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	369	351
Accretion expense	(22)	(18)
Liabilities settled	0	0
Revisions in estimates of cash flows	234	0
Liabilities incurred in the current year	139	0
Balance as of December 31	764	369
Duke Energy Ohio [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	27	27
Accretion expense	(1)	(2)
Liabilities settled	0	2
Revisions in estimates of cash flows	0	0
Liabilities incurred in the current year	0	0
Balance as of December 31	28	27
Duke Energy Indiana [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	43	46
Accretion expense	(1)	(2)
Liabilities settled	10	0
Revisions in estimates of cash flows	(1)	(9)
Liabilities incurred in the current year	4	4
Balance as of December 31	$ 37	$ 43