Related Party Transactions (Narrative)(Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Duke Energy Carolinas [Member]
DECAM Intercompany Loan Receivable	$ 811		$ 923
Dividend to parent	(250)	0
Duke Energy Ohio [Member]
DECAM Intercompany Loan Receivable	84		401
Dividend to parent	0	(485)
DECAM Intercompany Loan Payable	86		0
Duke Energy Indiana [Member]
DECAM Intercompany Loan Payable	55		300
DECAM [Member]
DECAM Intercompany Loan Receivable			90
DECAM Intercompany Loan Payable	$ 84