Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss)	$ 556.7	$ (764.2)	$ 1,527.1	$ 242.8
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	(15.0)	(28.6)	(22.6)	(20.8)
Securities Available for Sale, Net of Tax	0.9	0.5	2.7	1.7
Amortization of Pension and OPEB Deferred Costs, Net of Tax	0.3	0.2	0.8	0.4
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	(13.8)	(27.9)	(19.1)	(18.7)
TOTAL COMPREHENSIVE INCOME (LOSS)	542.9	(792.1)	1,508.0	224.1
Total Comprehensive Income Attributable to Noncontrolling Interest	12.0	1.6	15.2	5.3
TOTAL COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS	530.9	(793.7)	1,492.8	218.8
AEP Transmission Co [Member]
Net Income (Loss)	59.9	52.4	224.3	153.0
Appalachian Power Co [Member]
Net Income (Loss)	86.0	104.1	248.7	303.8
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	(0.1)	(0.2)	(0.5)	(0.6)
Amortization of Pension and OPEB Deferred Costs, Net of Tax	(0.3)	(0.3)	(0.9)	(1.0)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	(0.4)	(0.5)	(1.4)	(1.6)
TOTAL COMPREHENSIVE INCOME (LOSS)	85.6	103.6	247.3	302.2
Indiana Michigan Power Co [Member]
Net Income (Loss)	64.9	75.4	143.8	201.4
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	0.3	0.3	1.0	1.0
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	0.3	0.3	1.0	1.0
TOTAL COMPREHENSIVE INCOME (LOSS)	65.2	75.7	144.8	202.4
Ohio Power Co [Member]
Net Income (Loss)	82.6	99.9	231.1	244.7
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	(0.3)	(0.2)	(0.8)	(1.0)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)			(0.8)	(1.0)
TOTAL COMPREHENSIVE INCOME (LOSS)	82.3	99.7	230.3	243.7
Public Service Co Of Oklahoma [Member]
Net Income (Loss)	46.2	52.8	71.4	97.4
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	(0.2)	(0.2)	(0.6)	(0.6)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)			(0.6)	(0.6)
TOTAL COMPREHENSIVE INCOME (LOSS)	46.0	52.6	70.8	96.8
Southwestern Electric Power Co [Member]
Net Income (Loss)	84.1	84.4	126.5	153.2
OTHER COMPREHENSIVE INCOME
Cash Flow Hedges, Net of Tax	0.4	0.4	1.1	1.3
Amortization of Pension and OPEB Deferred Costs, Net of Tax	(0.2)	(0.1)	(0.5)	(0.5)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	0.2	0.3	0.6	0.8
TOTAL COMPREHENSIVE INCOME (LOSS)	84.3	84.7	127.1	154.0
Total Comprehensive Income Attributable to Noncontrolling Interest	11.0	1.1	12.6	3.3
TOTAL COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 73.3	$ 83.6	$ 114.5	$ 150.7