Derivatives and Hedging (Undesignated Contracts - Location and Amount of PreTax Gains and (Losses) Recognized in Income or As Regulatory Assets or Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on interest rate contracts recognized in earnings	$ (6)	$ (18)	$ (8)
Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings	(779)	(264)	(187)
Pretax gains (losses) recognized as regulatory assets or liabilities	(252)	80	44
Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(268)	10	(2)
Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	14	15	36
Nondesignated [Member] | Commodity Contracts [Member] | Revenue Regulated Electric [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings		11	(23)
Nondesignated [Member] | Commodity Contracts [Member] | Fuel Used In Electric Generation And Purchased Power Regulated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(44)	(200)	(194)
Nondesignated [Member] | Commodity Contracts [Member] | Income (loss) from Discontinued Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(729)	(57)	40
Nondesignated [Member] | Commodity Contracts [Member] | Other Income And Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings			(2)
Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities		55	10
Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	2
Duke Energy Carolinas [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings		(12)	(12)
Duke Energy Carolinas [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(19)
Duke Energy Carolinas [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Revenue Regulated Electric [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings		(12)	(12)
Progress Energy [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on interest rate contracts recognized in earnings	(4)	(17)	(8)
Progress Energy [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings	(48)	(206)	(466)
Pretax gains (losses) recognized as regulatory assets or liabilities	(229)	28	(165)
Progress Energy [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(233)	10	(171)
Progress Energy [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	2
Progress Energy [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Revenue Regulated Electric [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings		11	(11)
Progress Energy [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Fuel Used In Electric Generation And Purchased Power Regulated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(44)	(200)	(454)
Progress Energy [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Other Income And Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings			7
Progress Energy [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	2	18	6
Duke Energy Progress [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on interest rate contracts recognized in earnings		(13)	(6)
Duke Energy Progress [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings	(15)	(73)	(132)
Pretax gains (losses) recognized as regulatory assets or liabilities	(82)	7	(49)
Duke Energy Progress [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(82)	(6)	(55)
Duke Energy Progress [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Revenue Regulated Electric [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings		11	(11)
Duke Energy Progress [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Fuel Used In Electric Generation And Purchased Power Regulated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(15)	(71)	(115)
Duke Energy Progress [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities		13	6
Duke Energy Florida [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on interest rate contracts recognized in earnings	(4)	(5)	(2)
Duke Energy Florida [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings	(33)	(134)	(341)
Pretax gains (losses) recognized as regulatory assets or liabilities	(147)	21	(116)
Duke Energy Florida [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(151)	16	(116)
Duke Energy Florida [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Fuel Used In Electric Generation And Purchased Power Regulated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(29)	(129)	(339)
Duke Energy Florida [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	2	5
Duke Energy Florida [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	2
Duke Energy Ohio [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on interest rate contracts recognized in earnings	(1)	(1)	(1)
Duke Energy Ohio [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total pretax gains (losses) recognized in earnings	(759)	(57)	77
Pretax gains (losses) recognized as regulatory assets or liabilities	4	4	1
Duke Energy Ohio [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	1		2
Duke Energy Ohio [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	5		(1)
Duke Energy Ohio [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Income (loss) from Discontinued Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings	(758)	(56)	78
Duke Energy Ohio [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(2)	4
Duke Energy Indiana [Member] | Nondesignated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(7)	50	41
Duke Energy Indiana [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	(16)		2
Duke Energy Indiana [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities	9	16	35
Duke Energy Indiana [Member] | Nondesignated [Member] | Commodity Contracts [Member] | Revenue Regulated Electric [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) on commodity contracts recognized in earnings		1
Duke Energy Indiana [Member] | Nondesignated [Member] | Interest Rate Contracts [Member] | Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses) recognized as regulatory assets or liabilities		$ 34	$ 4