Related Party Transactions (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan receivable	$ 215		$ 382
Dividends paid to parent	(249)	0
Progress Energy [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan receivable	101		0
DECAM intercompany loan payable	858		455
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Dividends paid to parent	0	(310)
DECAM intercompany loan payable	257		364
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan receivable	0		207
Dividends paid to parent	(225)	(170)
DECAM intercompany loan payable	11		0
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan receivable	19		1
Transfer of Vermillion Generating Station	0	28
DECAM intercompany loan payable	602		245
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan receivable	21		0
Transfer of Vermillion Generating Station	0	26
DECAM intercompany loan payable	0		81
DECAM [Member]
Related Party Transaction [Line Items]
DECAM intercompany loan payable	$ 31		$ 79