Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Duke Energy Carolinas [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 178	$ 199	$ 377	$ 416
Duke Energy Carolinas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	5	12	11
Duke Energy Carolinas [Member] | Joint Dispatch Agreement [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	17	2	33	11
Related party transaction, expenses from transactions with related party	21	50	52	91
Duke Energy Carolinas [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1		2
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	173	160	342	334
Progress Energy [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	9	9	19	17
Progress Energy [Member] | Joint Dispatch Agreement [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	21	50	52	91
Related party transaction, expenses from transactions with related party	17	2	33	11
Progress Energy [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	19		38
Duke Energy Progress [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	102	89	205	189
Duke Energy Progress [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	3	4	7	7
Duke Energy Progress [Member] | Joint Dispatch Agreement [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	21	50	52	91
Related party transaction, expenses from transactions with related party	17	2	33	11
Duke Energy Progress [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	19		38
Duke Energy Florida [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	71	71	137	145
Duke Energy Florida [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	5	12	10
Duke Energy Ohio [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	84	87	174	172
Duke Energy Ohio [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1	2	2
Duke Energy Indiana [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	87	89	177	183
Duke Energy Indiana [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	2	2	4	4
Piedmont Natural Gas [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	8		14
Piedmont Natural Gas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			1
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	$ 20		$ 40
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party		1		2
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party		$ 19		$ 38