FAIR VALUE MEASUREMENTS - Fixed Income Securities Held in Nuclear Trusts (Details) - Spent Nuclear Fuel and Decommissioning Trusts $ in Millions |
Jun. 30, 2026
USD ($)
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|---|---|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |
| Within 1 year | $ 450 |
| After 1 year through 5 years | 608 |
| After 5 years through 10 years | 297 |
| After 10 years | 379 |
| Total | 1,734 |
| INDIANA MICHIGAN POWER COMPANY | |
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |
| Within 1 year | 450 |
| After 1 year through 5 years | 608 |
| After 5 years through 10 years | 297 |
| After 10 years | 379 |
| Total | $ 1,734 |
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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