Business Segments (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) segment	Mar. 31, 2016 USD ($)	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Income Attributable to Parent	$ 716	$ 694
Interest Expense	$ 491	489
Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 270	271
Interest Expense	$ 103	107
Progress Energy [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 199	209
Interest Expense	$ 206	160
Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 147	137
Interest Expense	$ 82	63
Duke Energy Florida [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 90	110
Interest Expense	$ 70	41
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	2
Net Income Attributable to Parent	$ 42	59
Interest Expense	$ 22	20
Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 91	95
Interest Expense	$ 44	44
Piedmont Natural Gas [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 95	103
Interest Expense	20	17
Other [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Interest Expense	$ 55	56
National Methanol Company [Member] | Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
SouthStar [Member] | Piedmont Natural Gas [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage			15.00%
Net Income Attributable to Parent		$ 7