Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Tax exempt bonds	$ (941,000,000)	$ (941,000,000)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	8,000,000,000
Commercial Paper	(3,022,000,000)
Outstanding letters of credit	(53,000,000)
Tax exempt bonds	(81,000,000)
Coal ash set-aside	(500,000,000)
Available capacity	4,344,000,000
Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	2,650,000,000
Commercial Paper	(917,000,000)
Outstanding letters of credit	(45,000,000)
Available capacity	1,688,000,000
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(243,000,000)	(243,000,000)
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	1,750,000,000
Commercial Paper	(739,000,000)
Outstanding letters of credit	(4,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	757,000,000
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(48,000,000)	(48,000,000)
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	1,400,000,000
Commercial Paper	(444,000,000)
Outstanding letters of credit	(2,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	704,000,000
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	650,000,000
Commercial Paper	(108,000,000)
Outstanding letters of credit	0
Available capacity	542,000,000
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(77,000,000)	(77,000,000)
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	450,000,000
Commercial Paper	(299,000,000)
Available capacity	151,000,000
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(572,000,000)	$ (572,000,000)
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	600,000,000
Commercial Paper	(317,000,000)
Tax exempt bonds	(81,000,000)
Available capacity	202,000,000
Piedmont Natural Gas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	500,000,000
Commercial Paper	(198,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity	300,000,000
Proceeds Loaned To Subsidiary Registrants [Member] | Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commercial Paper	$ (625,000,000)