Employee Benefit Plans (Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive income	[1]	$ (6)	$ (9)	$ 6
Progress Energy
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive income		1	(2)	$ (5)
Pension Plan | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(62)	(212)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		2	20
Amortization of prior year service credit		1	1
Amortization of prior year actuarial losses		(11)	(15)
Net amount recognized in accumulated other comprehensive income		(8)	6
Pension Plan | Duke Energy Carolinas | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(39)	(156)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Pension Plan | Progress Energy | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(26)	(79)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		1	1
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		(1)	(2)
Net amount recognized in accumulated other comprehensive income		0	(1)
Pension Plan | Duke Energy Progress | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(30)	(59)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Pension Plan | Duke Energy Florida | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		4	(20)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		1	(1)
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		(3)	3
Net amount recognized in accumulated other comprehensive income		(2)	2
Pension Plan | Duke Energy Ohio | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(2)	12
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Pension Plan | Duke Energy Indiana | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		5	22
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Pension Plan | Piedmont | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(1)	0
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		9	(127)
Regulatory liabilities, net increase (decrease)		(10)	(152)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		(1)	4
Net amount recognized in accumulated other comprehensive income		1	(4)
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		0	0
Regulatory liabilities, net increase (decrease)		(7)	1
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Progress Energy
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		9	(127)
Regulatory liabilities, net increase (decrease)		0	(149)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Duke Energy Progress
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		6	(82)
Regulatory liabilities, net increase (decrease)		0	(93)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Duke Energy Florida
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		3	(45)
Regulatory liabilities, net increase (decrease)		0	(56)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		0	0
Regulatory liabilities, net increase (decrease)		0	(1)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(4)	(5)
Regulatory liabilities, net increase (decrease)		(1)	(4)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		0	0
Other Post-Retirement Benefit Plans | Piedmont
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		0	0
Regulatory liabilities, net increase (decrease)		0	3
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year actuarial gain		0	0
Net amount recognized in accumulated other comprehensive income		$ 0	$ 0

[1] Net of income tax impacts of approximately $35 million for the year ended December 31, 2020. Tax impacts are immaterial for other periods presented.