Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Revolving Credit Facility [Member] - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000	$ 7,500,000,000.0
Commercial paper	(3,134,000,000)
Outstanding letters of credit	(71,000,000)
Tax exempt bonds	(81,000,000)
Coal ash set-aside	(500,000,000)
Available capacity	4,214,000,000
Parent Company [Member]
Line of Credit Facility [Line Items]
Facility size	3,400,000,000
Commercial paper	(1,822,000,000)
Outstanding letters of credit	(62,000,000)
Available capacity	1,516,000,000
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Facility size	1,100,000,000
Commercial paper	(469,000,000)
Outstanding letters of credit	(4,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	377,000,000
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Facility size	1,000,000,000
Commercial paper	(402,000,000)
Outstanding letters of credit	(2,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	346,000,000
Duke Energy Florida [Member]
Line of Credit Facility [Line Items]
Facility size	950,000,000
Outstanding letters of credit	(1,000,000)
Available capacity	949,000,000
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Facility size	450,000,000
Commercial paper	(30,000,000)
Available capacity	420,000,000
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(150,000,000)
Tax exempt bonds	(81,000,000)
Available capacity	369,000,000
Piedmont Natural Gas [Member]
Line of Credit Facility [Line Items]
Facility size	500,000,000	$ 850,000,000
Commercial paper	(261,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity	237,000,000
Proceeds Loaned To Subsidiary Registrants [Member] | Parent Company [Member]
Line of Credit Facility [Line Items]
Commercial paper	$ (625,000,000)