Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Cash Flow Hedges, Tax	$ (17.8)	$ (7.7)
Amortization of Pension and OPEB Deferred Costs, Tax	(0.5)	(0.4)
Appalachian Power Co [Member]
Cash Flow Hedges, Tax	(1.1)	(0.1)
Amortization of Pension and OPEB Deferred Costs, Tax	(0.3)	(0.2)
AEP Texas Inc. [Member]
Cash Flow Hedges, Tax	0.1	0.1
Indiana Michigan Power Co [Member]
Cash Flow Hedges, Tax	0.1	0.1
Amortization of Pension and OPEB Deferred Costs, Tax	0.0	0.0
Ohio Power Co [Member]
Cash Flow Hedges, Tax	0.0	(0.1)
Public Service Co Of Oklahoma [Member]
Cash Flow Hedges, Tax	(0.1)	(0.1)
Southwestern Electric Power Co [Member]
Cash Flow Hedges, Tax	0.1	0.1
Amortization of Pension and OPEB Deferred Costs, Tax	$ (0.1)	$ (0.1)

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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