Subsequent Events (Details) - Subsequent Event [Member] $ in Millions	2 Months Ended
	Feb. 25, 2021 USD ($)
Public Service Co Of Oklahoma [Member]
Estimated Natural Gas Expenses Associated with February 2021 Severe Weather	$ 175.0
Estimated Electricity Purchases Associated with February 2021 Severe Weather	650.0
Total Estimated Natural Gas Expenses and Electricity Purchase Associated with February 2021 Severe Weather	825.0
Notification from SPP for Additional Collateral Requirements Related to February 2021 Severe Weather	868.0
Southwestern Electric Power Co [Member]
Estimated Natural Gas Expenses Associated with February 2021 Severe Weather	375.0
Estimated Electricity Purchases Associated with February 2021 Severe Weather	0.0
Total Estimated Natural Gas Expenses and Electricity Purchase Associated with February 2021 Severe Weather	375.0
Notification from SPP for Additional Collateral Requirements Related to February 2021 Severe Weather	868.0
Minimum [Member] | Appalachian Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	65.0
Minimum [Member] | Southwestern Electric Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	30.0
Minimum [Member] | Kentucky Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	75.0
Maximum [Member] | Appalachian Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	75.0
Maximum [Member] | Southwestern Electric Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	40.0
Maximum [Member] | Kentucky Power Co [Member]
Total Estimated February 2021 Storm Restoration Expenditures	$ 95.0