Derivative Instruments	3 Months Ended
Mar. 31, 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 ratemaking 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 March 31, 2023, OTP had one outstanding pay-fixed, receive-variable swap agreement with an aggregate notional amount of 8,000 megawatt-hours of electricity, with a settlement date of December 31, 2023. As of March 31, 2023, the fair value of this derivative instrument was $0.3 million, which is included in other current 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. During the three months ended March 31, 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

3 Months Ended

Mar. 31, 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 ratemaking 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 March 31, 2023, OTP had one outstanding pay-fixed, receive-variable swap agreement with an aggregate notional amount of 8,000 megawatt-hours of electricity, with a settlement date of December 31, 2023. As of March 31, 2023, the fair value of this derivative instrument was $0.3 million, which is included in other current 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. During the three months ended March 31, 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.