Other Income and Expenses, Net Other Income and Expenses, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	$ 38	$ 57	$ 26
Foreign exchange gains (losses)	(4)	3	(18)
AFUDC equity	164	135	157
Post in-service equity returns	73	89	39
Nonoperating income (expense), other	36	67	58
Other income and expenses, net	307	351	262
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	4	1
AFUDC equity	96	91	91
Post in-service equity returns	60	71	32
Nonoperating income (expense), other	2	6	(4)
Other income and expenses, net	160	172	120
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	4	3	7
AFUDC equity	54	26	50
Post in-service equity returns	13	17	7
Nonoperating income (expense), other	26	31	30
Other income and expenses, net	97	77	94
Duke Energy Progress [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2		1
AFUDC equity	47	25	42
Post in-service equity returns	13	17	7
Nonoperating income (expense), other	9	9	7
Other income and expenses, net	71	51	57
Duke Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	2	3
AFUDC equity	7		8
Nonoperating income (expense), other	15	18	19
Other income and expenses, net	24	20	30
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	4	8	5
AFUDC equity	3	4	1
Nonoperating income (expense), other	(1)	(2)	(4)
Other income and expenses, net	6	10	2
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	6	6	6
AFUDC equity	11	14	15
Nonoperating income (expense), other	(6)	2	(3)
Other income and expenses, net	$ 11	$ 22	$ 18