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Historical Investment Balance used in purchase price accounting.

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Historical Investment Basis Difference. The difference between the historical investment price and th purchase price allocated to an investment.

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Percentage of an asset acquired when AEP does not purchase the entire asset.

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Production tax credits that are recorded in AEP's consolidated income Tax Expense (Benefit) total.

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Variable Interest carrying amount liabilities and equity.

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Wind Generation (MWs)

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No definition available.

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Portion of equity (net assets) in a variable interest entity (VIE) not attributable, directly or indirectly, to the parent entity. That is, this is the portion of equity in a VIE that is attributable to the noncontrolling interest (previously referred to as minority interest).

+ References

No definition available.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Carrying value of the regulatory asset that represents capitalized stranded costs that have been securitized (financed with debt) and are expected to be recoverable through a transition charge after one year (or beyond the operating cycle if longer). A transition charge is a charge approved by a regulator that allows deregulated utilities to recover investments in certain assets, such as power plants, over a transition period leading into a deregulated market.

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The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

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Variable Interest Entities and Equity Method Investments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) Rate	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Rate MW	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Securitization Bonds	$ 1,059.4		$ 1,059.4		$ 1,111.4
Securitized Transition Assets	938.7		938.7		920.6
Equity Method Investment Income	15.2	$ 18.1	51.1	$ 55.3
Apple Blossom and Black Oak [Member]
HLBV Income for Noncontrolling Interests	0.0		(4.0)
Variable Interest Entities (Textuals) [Abstract]
Noncontrolling Interest	$ 129.0		$ 129.0
Santa Rita East [Member]
Percentage of an Asset Acquired \| Rate	75.00%		75.00%
Variable Interest Entities (Textuals) [Abstract]
Noncontrolling Interest	$ 118.0		$ 118.0
Santa Rita East [Member] \| Total Generation MWs [Member]
Wind Generation MWs \| MW			302.4
Santa Rita East [Member] \| Long-term PPA MWs [Member]
Wind Generation MWs \| MW			260
Santa Rita East [Member] \| Sold at Wholesale MWs [Member]
Wind Generation MWs \| MW			42.4
Santa Rita East [Member] \| Consolidated VIE [Member]
Production Tax Credits			$ 8.0
Current Assets [Member] \| Apple Blossom and Black Oak [Member]
Assets [Abstract]
Assets	5.7		5.7
Current Assets [Member] \| Santa Rita East [Member]
Assets [Abstract]
Assets	17.0		17.0
Current Assets [Member] \| Restoration Funding [Member]
Assets [Abstract]
Assets	1.2		1.2
Net Property Plant And Equipment [Member] \| Apple Blossom and Black Oak [Member]
Assets [Abstract]
Assets	233.3		233.3
Net Property Plant And Equipment [Member] \| Santa Rita East [Member]
Assets [Abstract]
Assets	466.6		466.6
Net Property Plant And Equipment [Member] \| Restoration Funding [Member]
Assets [Abstract]
Assets	0.0		0.0
Other Noncurrent Assets [Member] \| Apple Blossom and Black Oak [Member]
Assets [Abstract]
Assets	12.5		12.5
Other Noncurrent Assets [Member] \| Santa Rita East [Member]
Assets [Abstract]
Assets	0.8		0.8
Other Noncurrent Assets [Member] \| Restoration Funding [Member]
Assets [Abstract]
Assets	235.3		235.3
Total Assets [Member] \| Apple Blossom and Black Oak [Member]
Assets [Abstract]
Assets	251.5		251.5
Total Assets [Member] \| Santa Rita East [Member]
Assets [Abstract]
Assets	484.4		484.4
Total Assets [Member] \| Restoration Funding [Member]
Assets [Abstract]
Assets	236.5		236.5
Current Liabilities [Member] \| Apple Blossom and Black Oak [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	2.2		2.2
Current Liabilities [Member] \| Santa Rita East [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	3.5		3.5
Current Liabilities [Member] \| Restoration Funding [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	14.4		14.4
Noncurrent Liabilities [Member] \| Apple Blossom and Black Oak [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	4.6		4.6
Noncurrent Liabilities [Member] \| Santa Rita East [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	7.5		7.5
Noncurrent Liabilities [Member] \| Restoration Funding [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	220.9		220.9
Equity [Member] \| Apple Blossom and Black Oak [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	244.7		244.7
Equity [Member] \| Santa Rita East [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	473.4		473.4
Equity [Member] \| Restoration Funding [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	1.2		1.2
Total Liabilities And Equity [Member] \| Apple Blossom and Black Oak [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	251.5		251.5
Total Liabilities And Equity [Member] \| Santa Rita East [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	484.4		484.4
Total Liabilities And Equity [Member] \| Restoration Funding [Member]
Liabilities and Equity [Abstract]
Variable Interest Carrying Amount Liabilities and Equity	$ 236.5		$ 236.5
JV Wind Farms [Member]
Equity Method Investment, Ownership Percentage \| Rate	50.00%		50.00%
Equity Method Investments	$ 389.0		$ 389.0
Historical Investment Balance	417.0		417.0
Historical Investment Basis Difference	(19.0)		(19.0)
Equity Method Investment Income	(3.0)		(6.0)
JV Wind Farms [Member] \| Equity Method Investment [Member]
Production Tax Credits	$ 7.0		$ 21.0
BP Wind Energy [Member]
Equity Method Investment, Ownership Percentage \| Rate	50.00%		50.00%
Berkshire Hathaway Energy [Member]
Equity Method Investment, Ownership Percentage \| Rate	50.00%		50.00%
AEP Transmission Holdco [Member]
Equity Method Investment, Ownership Percentage \| Rate	49.50%		49.50%
AEP Transmission Partner [Member]
Equity Method Investment, Ownership Percentage \| Rate	0.50%		0.50%
ETT [Member]
Equity Method Investment, Ownership Percentage \| Rate	50.00%		50.00%
Equity Method Investments	$ 693.0		$ 693.0		666.0
Equity Method Investment Income	16.0	$ 15.0	49.0	$ 46.0
AEP Texas Inc. [Member]
Securitized Transition Assets	698.1		698.1		$ 649.1
AEP Texas Inc. [Member] \| Restoration Funding [Member]
Securitization Bonds	235.0		235.0
Securitized Transition Assets	$ 235.0		$ 235.0