Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Excise Taxes)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			6 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2014	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 498	$ 602	$ 466
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	94	164	161
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	263	304	317
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	56	115	113
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	207	189	205
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	103	105	102
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	38	29	33
State [Member] | Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes	160
State [Member] | Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes	$ 110
Utility Franchise Tax Member [Member] | State [Member] | Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate				3.22%
Utility Franchise Tax Member [Member] | State [Member] | Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate				3.22%
Electricity Sales Tax Member [Member] | State [Member] | Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate				3.00%
Electricity Sales Tax Member [Member] | State [Member] | Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate				3.00%
Electricity Sales Tax Member [Member] | Current [Member] | State [Member] | Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate					7.00%
Electricity Sales Tax Member [Member] | Current [Member] | State [Member] | Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate					7.00%