Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
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	$ 197	$ 213	$ 409	$ 433
Duke Energy Carolinas [Member] | Indemnification coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	5	10	11
Duke Energy Carolinas [Member] | JDA [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	17	19	40	53
Related party transaction, expenses from transactions with related party	20	19	113	73
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	3	4	7	8
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	183	206	359	397
Progress Energy [Member] | Indemnification coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	10	9	19	17
Progress Energy [Member] | JDA [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	20	19	113	73
Related party transaction, expenses from transactions with related party	17	19	40	53
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	19	38	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	108	126	214	244
Duke Energy Progress [Member] | Indemnification coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	3	8	6
Duke Energy Progress [Member] | JDA [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	20	19	113	73
Related party transaction, expenses from transactions with related party	17	19	40	53
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	19	38	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	75	80	145	153
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	6	11	11
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	83	90	168	179
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	93	96	190	197
Duke Energy Indiana [Member] | Indemnification coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	2	3	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	37	40	69	76
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	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	22	23	45	46
Piedmont Natural Gas [Member] | Natural gas storage and transportation costs [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 6	$ 6	$ 11	$ 12