Summary of Significant Accounting (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
Jun. 30, 2010	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011
Goodwill impairment charge	$ 500,000,000	$ 175,000,000	$ 130,000,000
Other Current Liabilities		1,370,000,000		1,091,000,000
Percentage of current liabilities		5.00%
Duke Energy Corp [Member]
Accrued vacation		248,000,000		251,000,000
Duke Energy Ohio [Member]
Other Current Liabilities		135,000,000		122,000,000
Duke Energy Carolinas [Member]
Other Current Liabilities		$ 636,000,000		$ 398,000,000

Carrying value as of the balance sheet date of obligations incurred and payable for unused vacation time owed to employees based on the entity's vacation benefit given to its employees.

+ References+ Details

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

Aggregate carrying amount, as of the balance sheet date, of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered and of liabilities not separately disclosed in the balance sheet. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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