Variable Interest Entities (Sales and Cash Flows)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
CRC Receivable Sales	$ 2,154	$ 2,390	$ 2,858
Gain (Loss) on Sale of Accounts Receivable	(13)	(21)	(26)
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers	2,172	2,474	2,809
CRC Return Received on Retained Interests	5	12	15
CRC Collection Fees Received	1	1	1
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
CRC Receivable Sales	2,773	2,658	2,537
Gain (Loss) on Sale of Accounts Receivable	(12)	(16)	(17)
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers	2,784	2,674	2,474
CRC Return Received on Retained Interests	7	13	13
CRC Collection Fees Received	$ 1	$ 1	$ 1