Variable Interest Entities (Sales and Cash Flows)(Details) (Cinergy Receivables [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables sold	$ 487	$ 512	$ 1,228	$ 1,150
Loss recognized on sale	(2)	3	(6)	6
Cash proceeds from receivables sold	544	539	1,267	1,156
Collection fees received	1	1	1	1
Return received on retained interests	1	2	3	3
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables sold	679	702	1,434	1,449
Loss recognized on sale	(2)	3	(5)	6
Cash proceeds from receivables sold	713	721	1,474	1,446
Collection fees received	1	1	1	1
Return received on retained interests	$ 1	$ 1	$ 3	$ 3