Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) $ in Millions	Jun. 30, 2015 USD ($)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	$ 7,500
Commercial paper	(1,589)
Outstanding letters of credit	(71)
Tax exempt bonds	(116)
Coal ash set-aside	(500)
Available capacity	5,224
Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	3,200
Commercial paper	(972)
Outstanding letters of credit	(63)
Available capacity	2,165
Parent Company [Member] | Proceeds Loaned To Subsidiary Registrants [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commercial paper	(475)
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance Required	250
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	1,200
Commercial paper	(300)
Outstanding letters of credit	(4)
Tax exempt bonds	(35)
Coal ash set-aside	(250)
Available capacity	611
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance Required	250
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance Required	250
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	1,000
Commercial paper	(65)
Outstanding letters of credit	(3)
Coal ash set-aside	(250)
Available capacity	682
Duke Energy Progress [Member] | Revolving Credit Facility [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance Required	250
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	900
Commercial paper	(75)
Outstanding letters of credit	(1)
Available capacity	824
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	600
Commercial paper	(27)
Available capacity	573
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	600
Commercial paper	(150)
Tax exempt bonds	(81)
Available capacity	$ 369