Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Revolving Credit Facility [Member] $ in Millions	Mar. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Facility size	$ 7,500
Commercial paper	(2,980)
Outstanding letters of credit	(79)
Tax exempt bonds	(116)
Coal ash set-aside	(500)
Available capacity	3,825
Parent Company [Member]
Line of Credit Facility [Line Items]
Facility size	3,475
Commercial paper	(1,816)
Outstanding letters of credit	(72)
Available capacity	1,587
Parent Company [Member] | Proceeds Loaned To Subsidiary Registrants [Member]
Line of Credit Facility [Line Items]
Commercial paper	(625)
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Facility size	800
Commercial paper	(300)
Outstanding letters of credit	(4)
Tax exempt bonds	(35)
Coal ash set-aside	(250)
Available capacity	211
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Facility size	1,000
Commercial paper	(205)
Outstanding letters of credit	(2)
Coal ash set-aside	(250)
Available capacity	543
Duke Energy Florida [Member]
Line of Credit Facility [Line Items]
Facility size	1,200
Commercial paper	(480)
Outstanding letters of credit	(1)
Available capacity	719
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Facility size	425
Commercial paper	(29)
Available capacity	396
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Facility size	600
Commercial paper	(150)
Tax exempt bonds	(81)
Available capacity	$ 369