Severance (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010 Duke Energy Corp [Member]
Number of employees that accepted the termination benefits	900	500
Number of eligible employees		4,850
Restructuring reserve, beginning balance		$ 87,000,000
Provision/Adjustments to severance liability		(2,000,000)
Cash reductions to severance liability		(53,000,000)
Restructuring reserve, ending balance		32,000,000
Severance expense		$ 80,000,000	$ 172,000,000	[1]

[1] These amounts are recorded in Operation, Maintenance and Other within Operating Expenses on the Consolidated Statements of Operations.