Other Income and Expenses, Net Other Income and Expenses, Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	$ 57	$ 26	$ 50
Foreign exchange gains (losses)	3	(18)	4
Equity component of AFUDC	135	157	300
Deferred returns	89duk_DeferredReturns	39duk_DeferredReturns	24duk_DeferredReturns
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Other income and expenses, net	351us-gaap_OtherNonoperatingIncomeExpense	262us-gaap_OtherNonoperatingIncomeExpense	397us-gaap_OtherNonoperatingIncomeExpense
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	4	1	11
Equity component of AFUDC	91	91	154
Deferred returns	71	32	24
Other income (expense)	6	(4)	(4)
Other income and expenses, net	172	120	185
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	3	7	2
Equity component of AFUDC	26	50	106
Deferred returns	17	7
Other income (expense)	31	30	22
Other income and expenses, net	77	94	130
Duke Energy Progress [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		1	1
Equity component of AFUDC	25	42	69
Deferred returns	17	7
Other income (expense)	9	7	9
Other income and expenses, net	51	57	79
Duke Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	3	1
Equity component of AFUDC		8	37
Other income (expense)	18	19	1
Other income and expenses, net	20	30	39
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	8	5
Equity component of AFUDC	4	1	6
Other income (expense)	(2)	(4)	2
Other income and expenses, net	10	2	8
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	6	6	7
Equity component of AFUDC	14	15	84
Other income (expense)	2	(3)	(1)
Other income and expenses, net	$ 22	$ 18	$ 90

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Total increase in earnings in the period representing the cost of equity allowed to be added to completed construction projects which are not yet recovered in retail rates.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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The component of the allowance for funds used during construction during the period based on an assumed rate of return on equity funds used in financing the construction of regulated assets.

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