Summary of Significant Accounting Policies (Narrative)(Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Oct. 03, 2016	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015
Restricted Cash [Abstract]
Restricted cash			$ 137	$ 98
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]
Payments to Acquire Businesses, Gross			10	1,249
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Payments to Acquire Businesses, Gross				$ 1,249
Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes			$ 110
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%
Piedmont Natural Gas [Member]
Organization And Basis Of Presentation [Line Items]
Payments to Acquire Businesses, Gross	$ 5,000