Summary of Significant Accounting Policies (Narrative)(Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended			96 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2022
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 209		$ 30	$ 209
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			170	152
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	2,036		857	2,036	$ 1,501
Restricted Cash [Abstract]
Restricted cash	298		108	298
Duke Energy Carolinas [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	13		13	13	23
Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes				160
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	23		30	23
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	42		44	42	58
Duke Energy Progress [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	9		15	9	21
Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes				110
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	23		30	23
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	8		8	8	16
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	186			186
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	20		14	20	36
Duke Energy Indiana [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	$ 6		9	$ 6	$ 15
International Energy [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period			534
Foreign Earnings Repatriated			$ 1,500
Restricted Cash [Abstract]
Cash Repatriation period			8 years
International Energy [Member] | Scenario, Forecast [Member]
Cash and Cash Equivalents [Abstract]
Foreign Earnings Repatriated						$ 2,700
Utility Franchise Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.22%
Utility Franchise Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.22%
Electricity Sales Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.00%
Electricity Sales Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.00%
Current [Member] | Electricity Sales Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate	7.00%
Current [Member] | Electricity Sales Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate	7.00%