Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash Flow Hedges, Tax	$ (8.1)	$ (15.4)	$ (12.2)	$ (11.2)
Securities Available for Sale, Tax	0.5	0.3	1.5	1.0
Amortization of Pension and OPEB Deferred Costs, Tax	0.1	0.1	0.4	0.2
Appalachian Power Co [Member]
Cash Flow Hedges, Tax	(0.1)	(0.1)	(0.3)	(0.3)
Amortization of Pension and OPEB Deferred Costs, Tax	(0.1)	(0.1)	(0.4)	(0.5)
Indiana Michigan Power Co [Member]
Cash Flow Hedges, Tax	0.1	0.1	0.5	0.5
Ohio Power Co [Member]
Cash Flow Hedges, Tax	(0.1)	(0.1)	(0.4)	(0.5)
Public Service Co Of Oklahoma [Member]
Cash Flow Hedges, Tax	(0.1)	(0.1)	(0.3)	(0.3)
Southwestern Electric Power Co [Member]
Cash Flow Hedges, Tax	0.2	0.2	0.6	0.7
Amortization of Pension and OPEB Deferred Costs, Tax	$ (0.1)	$ (0.1)	$ (0.3)	$ (0.3)

Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e640-108580

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