Employee Benefit Plans (Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive income	[1]	$ (9)	$ 6	$ (3)
Progress Energy
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive income		(2)	(5)	$ (4)
Pension Plan | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(212)	298
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		20	(2)
Amortization of prior year service credit		1	1
Amortization of prior year actuarial losses		(15)	10
Net amount recognized in accumulated other comprehensive income		6	9
Pension Plan | Duke Energy Carolinas | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(156)	170
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)		(79)	40
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		(2)	(4)
Net amount recognized in accumulated other comprehensive income		(1)	(3)
Pension Plan | Duke Energy Progress | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(59)	31
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)		(20)	9
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		(1)	0
Amortization of prior year service credit		0	0
Amortization of prior year actuarial losses		3	0
Net amount recognized in accumulated other comprehensive income		2	0
Pension Plan | Duke Energy Ohio | Qualified Plan
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		12	10
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)		22	30
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)		0	8
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)		(127)	137
Accumulated other comprehensive loss (income)		(152)	154
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	(1)
Amortization of prior year prior service cost		(4)	1
Net amount recognized in accumulated other comprehensive income		(4)	0
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		0	0
Accumulated other comprehensive loss (income)		1	(6)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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)		(127)	133
Accumulated other comprehensive loss (income)		(149)	149
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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)		(82)	84
Accumulated other comprehensive loss (income)		(93)	93
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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)		(45)	49
Accumulated other comprehensive loss (income)		(56)	56
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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
Accumulated other comprehensive loss (income)		(1)	2
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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)		(5)	(5)
Accumulated other comprehensive loss (income)		(4)	3
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		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	4
Accumulated other comprehensive loss (income)		3	0
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		0	0
Amortization of prior year prior service cost		0	0
Net amount recognized in accumulated other comprehensive income		$ 0	$ 0

[1] Tax impacts are insignificant for all periods presented.