Debt And Credit Facilities (Schedule Of Line Of Credit Facilities) (Details) (Master Credit Facility [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Facility Size	$ 4,000
Outstanding Letters of Credit	(27)
Notes Payable and Commercial Paper	(1,034)
Tax Exempt Bonds	(260)
Available Capacity	2,679
Duke Energy Corp [Member]
Facility Size	1,250
Outstanding Letters of Credit	(20)
Notes Payable and Commercial Paper	(518)
Tax Exempt Bonds	0
Available Capacity	712
Duke Energy Carolinas [Member]
Facility Size	1,250
Outstanding Letters of Credit	(7)
Notes Payable and Commercial Paper	(300)
Tax Exempt Bonds	(95)
Available Capacity	848
Duke Energy Ohio [Member]
Facility Size	750
Outstanding Letters of Credit	0
Notes Payable and Commercial Paper	0
Tax Exempt Bonds	(84)
Available Capacity	666
Duke Energy Indiana [Member]
Facility Size	750
Outstanding Letters of Credit	0
Notes Payable and Commercial Paper	(216)
Tax Exempt Bonds	(81)
Available Capacity	$ 453