Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure) (Details) $ in Millions	Dec. 31, 2021 USD ($) $ / MWh	Dec. 31, 2020 USD ($) $ / MWh	Dec. 31, 2019 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $	$ (121)	$ (77)	$ (102)
Forward natural gas curves – price per MMBtu | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $		$ (84)
Forward natural gas curves – price per MMBtu | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $	$ (145)
Forward natural gas curves – price per MMBtu | Minimum | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)		14.68
Forward natural gas curves – price per MMBtu | Minimum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	19.04
Forward natural gas curves – price per MMBtu | Maximum | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)		151.84
Forward natural gas curves – price per MMBtu | Maximum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	139.11
Forward natural gas curves – price per MMBtu | Weighted Average | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)		28.84
Forward natural gas curves – price per MMBtu | Weighted Average | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	37.57
Duke Energy Ohio | FTR price – per MWh | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $	$ 2	$ 1
Duke Energy Ohio | FTR price – per MWh | Minimum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	0.06	0.25
Duke Energy Ohio | FTR price – per MWh | Maximum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	1.79	1.68
Duke Energy Ohio | FTR price – per MWh | Weighted Average | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	0.96	0.79
Duke Energy Indiana
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $	$ 22	$ 6	$ 11
Duke Energy Indiana | FTR price – per MWh | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net derivative asset (liability) | $	$ 22	$ 6
Duke Energy Indiana | FTR price – per MWh | Minimum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	(1.18)	(2.40)
Duke Energy Indiana | FTR price – per MWh | Maximum | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	13.11	7.41
Duke Energy Indiana | FTR price – per MWh | Weighted Average | RTO auction pricing
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input measurement (in usd per MWh and usd per MMBtu)	2.68	1.05