Income Taxes (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)
Income Taxes (Textuals) [Abstract]
Valuation Allowance	$ 9	$ 9
Transmission and Distribution Expenses Net Income Adjustment		21
Certain Assets Held for Sale and 2015 Federal Income Tax Return
Income Taxes (Textuals) [Abstract]
Valuation Allowance Adjustment	$ 66
Public Service Co Of Oklahoma [Member]
Income Taxes (Textuals) [Abstract]
Transmission and Distribution Expenses Net Income Adjustment		2
Southwestern Electric Power Co [Member]
Income Taxes (Textuals) [Abstract]
Transmission and Distribution Expenses Net Income Adjustment		$ 9