Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Other Assets and Liabilities)(Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Collateral assets	$ 209	$ 135
Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	638	621
Duke Energy Carolinas [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	216	198
Collateral liabilities	128	120
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Collateral assets	23	10
Progress Energy [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	718	119
Progress Energy [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	174	214
Customer deposits	360	349
Derivative liabilities	271
Duke Energy Progress [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	272	15
Duke Energy Progress [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	116	121
Customer deposits	135	129
Derivative liabilities	108	38
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Collateral assets	23	10
Duke Energy Florida [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	177	65
Duke Energy Florida [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	57	65
Customer deposits	225	220
Derivative liabilities	163
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Collateral assets	186	125
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Collateral assets	13	122
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	98	56
Duke Energy Indiana [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	25	25
Collateral liabilities	$ 43	$ 40