SIGNIFICANT ACCOUNTING MATTERS - Reconciliation of Cash (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Significant Accounting Matters [Line Items]
Cash and Cash Equivalents	$ 256.8	$ 202.9
Restricted Cash	35.2	43.1
Total Cash, Cash Equivalents and Restricted Cash	292.0	246.0	$ 281.8	$ 379.0
AEP Texas
Significant Accounting Matters [Line Items]
Cash and Cash Equivalents	0.1	0.1
Restricted Cash	13.4	23.5
Total Cash, Cash Equivalents and Restricted Cash	13.5	23.6	42.8	34.1
APCo
Significant Accounting Matters [Line Items]
Cash and Cash Equivalents	8.7	3.9
Restricted Cash	10.6	16.2
Total Cash, Cash Equivalents and Restricted Cash	19.3	20.1	16.0	19.9
SWEPCo
Significant Accounting Matters [Line Items]
Cash and Cash Equivalents	3.4	1.2
Restricted Cash	11.2	3.4
Total Cash, Cash Equivalents and Restricted Cash	$ 14.6	$ 4.6	$ 3.8	$ 2.4

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-8

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-24

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-4

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant