Acquisitions and Dispositions (Assets Held For Sale) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets	$ 409
Current liabilities	271	7
Duke Energy Ohio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets	359
Current liabilities	257
Midwest Generation Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets	409
Investments and other assets	42
Property, plant and equipment	2,153
Total assets held for sale	2,604
Current liabilities	271
Deferred credits and other liabilities	75
Total liabilities associated with assets held for sale	346
Midwest Generation Business [Member] | Duke Energy Ohio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets	359
Investments and other assets	37
Property, plant and equipment	2,116
Total assets held for sale	2,512
Current liabilities	257
Deferred credits and other liabilities	74
Total liabilities associated with assets held for sale	$ 331