Derivative Instruments	9 Months Ended
	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative InstrumentsOTP enters into derivative instruments to manage its exposure to future 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 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, 2022, OTP had outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 156,800 megawatt-hours of electricity, which will be settled periodically throughout 2022 and 2023. As of September 30, 2022, the fair value of these derivative instruments was $5.4 million, of which $5.5 million is included in other current assets and $0.1 million, which is included in other noncurrent liabilities, on the consolidated balance sheets. As of December 31, 2021, the fair value of these types of derivative contracts was $6.2 million, which is included in other current assets. No contracts settled during the three months ended September 30, 2022. During the nine months ended September 30, 2022, contracts matured and were settled in an aggregate amount of $2.8 million. There were no contracts settled during the three or nine months ended September 30, 2021