Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Line of Credit Facility [Line Items]
Facility size	$ 6,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	6,000	[1]
Commercial paper	(1,278)	[2]
Outstanding letters of credit	(64)
Tax exempt bonds	(116)
Available capacity	4,542
Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	2,250	[1]
Commercial paper	(784)	[2]
Outstanding letters of credit	(56)
Tax exempt bonds	0
Available capacity	1,410
Parent Company [Member] | Proceeds Loaned To Subsidiary Registrants [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commercial paper	(450)
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	1,000	[1]
Commercial paper	(300)	[2]
Outstanding letters of credit	(4)
Tax exempt bonds	(35)
Available capacity	661
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	750	[1]
Commercial paper	(27)
Outstanding letters of credit	(2)
Tax exempt bonds	0
Available capacity	721
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	650	[1]
Commercial paper	0
Outstanding letters of credit	(1)
Tax exempt bonds	0
Available capacity	649
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	650	[1]
Commercial paper	(4)
Outstanding letters of credit	0
Tax exempt bonds	0
Available capacity	646
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	700	[1]
Commercial paper	(163)	[2]
Outstanding letters of credit	(1)
Tax exempt bonds	(81)
Available capacity	$ 455

[1] Represents the sublimit of each borrower.

[2] Duke Energy issued $450 million of commercial paper and loaned the proceeds through the money pool to Duke Energy Carolinas and Duke Energy Indiana. The balances are classified within Long-Term Debt Payable to Affiliated Companies in Duke Energy Carolinas' and Duke Energy Indiana’s Condensed Consolidated Balance Sheets.