Derivative Instruments	9 Months Ended
Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative InstrumentsOTP enters into derivative instruments to manage its exposure to future market energy price variability and reduce volatility in prices for our retail customers. These derivative instruments are not designated as qualifying hedging transactions but provide for an economic hedge against future market energy price variability. The instruments are recorded at fair value on the consolidated balance sheets. In accordance with rate-making and cost recovery processes, we recognize a regulatory asset or liability to defer losses or gains from derivative activity until settlement of the associated derivative instrument. As of September 30, 2023, OTP had multiple outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 195,400 megawatt-hours of electricity, with various settlement dates extending to December 31, 2024. As of September 30, 2023, the fair value of these derivative instruments was $1.5 million, of which $1.2 million is included in other current liabilities and $0.3 million is included in other noncurrent liabilities on the consolidated balance sheets. As of December 31, 2022, the fair value of these types of derivative contracts was $7.1 million, which is included in other current liabilities. There were no contracts which matured during the three months ended September 30, 2023 or 2022. During the nine months ended September 30, 2023 and 2022, contracts matured and were settled in an aggregate amount of a $16.0 million loss and a $2.8 million gain, respectively. Gains and losses recognized on the settlement of derivative instruments are recorded in electric purchased power in the consolidated statements of income. Such settlement gains and losses are returned to or recovered from our electric customers through fuel recovery mechanisms in each state.

Derivative Instruments

9 Months Ended

Sep. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative InstrumentsOTP enters into derivative instruments to manage its exposure to future market energy price variability and reduce volatility in prices for our retail customers. These derivative instruments are not designated as qualifying hedging transactions but provide for an economic hedge against future market energy price variability. The instruments are recorded at fair value on the consolidated balance sheets. In accordance with rate-making and cost recovery processes, we recognize a regulatory asset or liability to defer losses or gains from derivative activity until settlement of the associated derivative instrument. As of September 30, 2023, OTP had multiple outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 195,400 megawatt-hours of electricity, with various settlement dates extending to December 31, 2024. As of September 30, 2023, the fair value of these derivative instruments was $1.5 million, of which $1.2 million is included in other current liabilities and $0.3 million is included in other noncurrent liabilities on the consolidated balance sheets. As of December 31, 2022, the fair value of these types of derivative contracts was $7.1 million, which is included in other current liabilities. There were no contracts which matured during the three months ended September 30, 2023 or 2022. During the nine months ended September 30, 2023 and 2022, contracts matured and were settled in an aggregate amount of a $16.0 million loss and a $2.8 million gain, respectively. Gains and losses recognized on the settlement of derivative instruments are recorded in electric purchased power in the consolidated statements of income. Such settlement gains and losses are returned to or recovered from our electric customers through fuel recovery mechanisms in each state.