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v3.25.1

BORROWINGS - Narrative (Details) |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 18, 2024 | Nov. 01, 2013 USD ($) investor | Mar. 31, 2025 USD ($) | Mar. 31, 2024 USD ($) | Sep. 30, 2024 USD ($) | Dec. 31, 2024 USD ($) | Jun. 30, 2024 USD ($) | Dec. 18, 2019 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Total available remaining borrowing capacity from FHLB |  |  | $ 625,400,000 |  |  |  |  |
Putable advances with the FHLB |  |  | 972,478,000 |  |  | $ 822,554,000 |  |
Debt face amount |  | $ 70,000,000 |  |  |  |  |  |
Private debt issuance, number of institutional investors | investor |  | 4 |  |  |  |  |  |
5.00% Senior Notes Due 2028 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Redemption price (percent) |  | 100.00% |  |  |  |  |  |
Senior Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Fixed interest rate term |  | 10 years |  |  |  |  |  |
U.S. Bank, N.A | Line of Credit |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  |  | 2.25% |  |  |
Outstanding balance on the line of credit |  |  | 0 |  |  | 0 |  |
Maximum borrowing capacity |  |  |  |  | $ 75,000,000 |  |  |
Non-refundable facility fee |  |  |  |  | 0.40% |  |  |
Putable Advances |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Putable advances with the FHLB |  |  | $ 355,000,000 |  |  |  |  |
Minimum |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Interest rate, minimum (as a percent) |  |  | 1.50% |  |  |  |  |
Maximum |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Interest rate, minimum (as a percent) |  |  | 4.83% |  |  |  |  |
Securities Sold Under Repurchase Agreements |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Maximum amount of outstanding agreements |  |  | $ 169,100,000 | $ 194,200,000 |  |  |  |
Total of average agreements |  |  | 159,300,000 | 172,700,000 |  |  |  |
Debt outstanding |  |  | 122,947,000 |  |  |  |  |
Subordinated Debentures and Term Loans |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt outstanding |  |  | 62,619,000 |  |  |  |  |
Subordinated Debenture | 6.75% Subordinated Notes Due 2028 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt face amount |  | $ 65,000,000 |  |  |  |  |  |
Interest rate on notes (as a percent) |  | 6.75% |  |  |  |  |  |
Redemption price (percent) |  | 100.00% |  |  |  |  |  |
Redeemed |  |  |  | $ 40,000,000 |  |  | $ 25,000,000 |
Subordinated Debenture | Level One Subordinated Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt face amount |  |  |  |  |  |  |  | $ 30,000,000
Basis spread on variable rate (as a percent) | 3.11% |  |  |  |  |  |  |
Interest rate on notes (as a percent) |  |  |  |  |  |  |  | 4.75%
Redeemed |  |  | 30,000,000 |  |  |  |  |
Principal amount outstanding |  |  | 0 |  |  |  |  |
Subordinated Debenture | First Merchant Capital Trust II |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt face amount |  |  | $ 41,700,000 |  |  | $ 41,700,000 |  |
Basis spread on variable rate (as a percent) |  |  | 0.26161% |  |  | 0.26161% |  |
Interest rate during the period |  |  | 6.12% |  |  | 6.18% |  |
Subordinated Debenture | Ameriana Capital Trust I |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt face amount |  |  | $ 10,300,000 |  |  | $ 10,300,000 |  |
Basis spread on variable rate (as a percent) |  |  | 0.26161% |  |  | 0.26161% |  |
Interest rate during the period |  |  | 6.06% |  |  | 6.12% |  |
Senior Notes | 5.00% Senior Notes Due 2028 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt face amount |  | $ 5,000,000 |  |  |  |  |  |
Interest rate on notes (as a percent) |  | 5.00% |  |  |  |  |  |
Senior Notes | First Merchants Senior Notes and Subordinated Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt, weighted average interest rate |  |  | 6.90% |  |  | 7.18% |  |
Senior Notes | First Merchants Senior Notes and Subordinated Notes | Secured Overnight Financing Rate (SOFR) |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  | 0.26161% |  |  | 0.26161% |  |
Senior Notes | First Merchants Senior Notes and Subordinated Notes | Base Rate |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  | 2.345% |  |  | 2.345% |  |
Secured Debt |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt outstanding |  |  |  |  |  | $ 7,100,000 |  |
Interest rate on notes (as a percent) |  |  | 3.41% |  |  | 3.41% |  |
Secured Debt | Level One |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt outstanding |  |  | $ 1,100,000 |  |  | $ 1,100,000 |  |
Interest rate on notes (as a percent) |  |  | 1.00% |  |  | 1.00% |  |

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