Severance Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring Liability, beginning balance	$ 135
Provision/Adjustments	31	[1]
Cash Reductions	(67)
Restructuring Liability, ending balance	99
Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Liability, beginning balance	12
Provision/Adjustments	1
Cash Reductions	(9)
Restructuring Liability, ending balance	4
Progress Energy [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Liability, beginning balance	43
Provision/Adjustments	21	[1]
Cash Reductions	(18)
Restructuring Liability, ending balance	46
Duke Energy Progress [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Liability, beginning balance	23
Provision/Adjustments	1
Cash Reductions	(10)
Restructuring Liability, ending balance	14
Duke Energy Florida [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Liability, beginning balance	6
Provision/Adjustments	16	[1]
Cash Reductions	(2)
Restructuring Liability, ending balance	$ 20

[1] Provision / Adjustments includes $16 million of severance costs deferred related to Crystal River Unit 3.