Related Party Transactions (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	9 Months Ended
	Jan. 12, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Related Party Transaction [Line Items]
Debt instrument, face amount		$ 3,771
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable		595		382
Dividends to parent		(500)	(250)
Progress Energy [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable		103		0
Intercompany loan payable		1,195		455
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Dividends to parent		0	(310)
Intercompany loan payable		581		364
Debt instrument, face amount		548
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable		30		207
Dividends to parent		(225)	(170)
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable		46		1
Transfer of Vermillion Generating Station	28		28
Intercompany loan payable		69		245
Debt instrument, face amount		450
Duke Energy Ohio [Member] | DECAM [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable			46
Intercompany loan payable				79
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Intercompany loan receivable		69		0
Dividends to parent		(125)	0
Transfer of Vermillion Generating Station	26	0	26
Intercompany loan payable		0		81
Debt instrument, face amount		$ 500