Schedule I - Condensed Parent Company Financials (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Nov. 13, 2012	Oct. 31, 2012	Jul. 02, 2012	Nov. 30, 2011	Apr. 04, 2011
Condensed Financial Statements, Captions
Guarantor Obligations, Current Carrying Value	$ 41,000,000	$ 19,000,000
Notes receivable	71,000,000	62,000,000
Other Nonoperating Income	28,000,000	51,000,000	53,000,000
Investment balance	64,000,000
Investment balance, debt obligations	64,000,000
Parent Company [Member]
Condensed Financial Statements, Captions
Principal amount of senior notes				1,000,000,000
Unsecured Variable Denomination Floating Rate Demand Notes, Amount Available For Sale								1,000,000,000
Line Of Credit Facility, Conditional Capacity								500,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted	6,100,000,000
Payments For Contributed Capital	16,000,000	15,000,000
DebtInstrumentDecreaseForgiveness			29,000,000
ProceedsFromDividendsReceived	450,000,000	299,000,000	350,000,000
Line of Credit Facility, Maximum Borrowing Capacity					5,630,000,000	2,000,000,000	6,000,000,000
Investment balance	395,000,000	79,000,000
Investment balance, debt obligations	36,000,000
Money Pool Interest Income	11,000,000	4,000,000	7,000,000
Duke Energy Carolinas [Member]
Condensed Financial Statements, Captions
Other Nonoperating Income	(4,000,000)	(2,000,000)	0
Duke Energy Indiana [Member]
Condensed Financial Statements, Captions
Other Nonoperating Income	(1,000,000)	(5,000,000)	0
Available At Closing [Member] | Parent Company [Member]
Condensed Financial Statements, Captions
Line of Credit Facility, Maximum Borrowing Capacity							$ 4,000,000,000