Other Income and Expenses, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	$ 13	$ 21	$ 20
AFUDC equity	237	200	164
Post in-service equity returns	40	67	73
Nonoperating income (expense), other	62	36	33
Other income and expenses, net	352	324	290
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	4	2
AFUDC equity	106	102	96
Post in-service equity returns	28	55	60
Nonoperating income (expense), other	3	1	2
Other income and expenses, net	139	162	160
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	6	4	4
AFUDC equity	92	76	54
Post in-service equity returns	12	12	13
Nonoperating income (expense), other	18	22	26
Other income and expenses, net	128	114	97
Duke Energy Progress [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	3	2
AFUDC equity	47	50	47
Post in-service equity returns	12	12	13
Nonoperating income (expense), other	4	6	9
Other income and expenses, net	65	71	71
Duke Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	5	2	2
AFUDC equity	45	26	7
Nonoperating income (expense), other	11	16	15
Other income and expenses, net	61	44	24
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	6	5	4
AFUDC equity	11	6	3
Nonoperating income (expense), other		(2)	(1)
Other income and expenses, net	17	9	6
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	8	6	6
AFUDC equity	28	16	11
Nonoperating income (expense), other	1		(6)
Other income and expenses, net	$ 37	$ 22	$ 11