Regulatory Matters (Schedule of Crystal River Unit 3 Regulatory Asset) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	$ 10,864		$ 11,004
Duke Energy Carolinas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	1,836		1,727
Progress Energy [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	5,193		5,292
Duke Energy Progress [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	1,905		1,845
Duke Energy Florida [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	3,167		3,321
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Total regulatory assets	1,497
Duke Energy Florida [Member] | Historical Net Book Value [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	1,036	[1]
Duke Energy Florida [Member] | Operating Expense Deferrals [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	96	[2]
Duke Energy Florida [Member] | Carrying Charges [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	33	[3]
Duke Energy Florida [Member] | Amount Subject To Cost Cap [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	1,165
Duke Energy Florida [Member] | Uprate And Dry Cask Storage Projects [Member] | Crystal River Unit 3 [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	332
Duke Energy Ohio [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	564		579
Duke Energy Indiana [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets, noncurrent	$ 769		$ 810

[1] Includes amounts previously classified as plant in service, construction work in process, nuclear fuel and materials and supplies inventory.

[2] Includes operations and maintenance, property taxes and depreciation.

[3] See discussion under Customer Rate Matters section below.