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Stock Based Compensation - Additional Information (Detail) - USD ($) |  |  |  |  |  | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 18, 2024 | Nov. 18, 2023 | Jun. 01, 2023 | May 25, 2023 | Nov. 18, 2021 | Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of shares committed to be released each year, ESOP |  |  |  |  |  | 7,678 |  | 7,678 |  | 9,966 | [1]
Unearned compensation for ESOP |  |  |  |  |  | $ 4,628,000 |  | $ 4,628,000 |  | $ 2,637,000 |
Stock options granted, outstanding |  |  |  | 249,144 |  |  |  | 249,144 |  | 0 |
Share price |  |  | $ 7.99 |  |  |  |  | $ 0 |  | $ 0 |
Share based expense recognized |  |  |  |  |  | 99,000 | $ 98,000 | $ 195,000 | $ 197,000 |  |
Income tax (benefit) expense |  |  |  |  |  | 280,000 | (66,000) | $ 240,000 | (124,000) |  |
Weighted average future recognition period |  |  |  |  |  |  |  | 1 year 4 months 24 days |  | 1 year 10 months 24 days |
Restricted stock awards granted |  |  | 2,478 |  |  |  |  | 2,478 |  | 0 |
Fair value related to grant |  |  | $ 20,000 |  |  |  |  |  |  |  |
Director [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share based expense recognized |  |  |  |  |  | 21,000 |  |  |  |  |
Restricted Stock Awards [Member] | Directors and Members [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Restricted Stock Award, |  |  |  |  | 98,850 |  |  |  |  |  |
Share price |  |  |  |  |  |  |  | $ 11.95 |  |  |
Total fair value related to stock options granted |  |  |  |  |  |  |  | $ 1,200,000 |  |  |
Restricted Stock Awards [Member] | Scenario Forecast [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Restricted stock awards time-vest | 50.00% | 50.00% |  |  |  |  |  |  |  |  |
Minimum [Member] | Restricted Stock Awards [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issued stock option granted, term |  |  |  |  |  |  |  | 3 years |  |  |
2021 Equity Incentive Plan [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Unearned compensation for ESOP |  |  |  |  |  | 534,000 |  | $ 534,000 |  | $ 729,000 |
Common stock shares issued during period, new issues |  |  |  |  |  |  |  | 348,802 |  |  |
Issued stock option granted, term |  |  |  |  |  |  |  | 10 years |  |  |
Income tax (benefit) expense |  |  |  |  |  | (26,000) | (27,000) | $ (51,000) | (53,000) |  |
2021 Equity Incentive Plan [Member] | Director [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Unearned compensation for ESOP |  |  |  |  |  | 727,000 |  | 727,000 |  |  |
Share based expense recognized |  |  |  |  |  |  | 0 | 21,000 | 0 |  |
Income tax (benefit) expense |  |  |  |  |  | $ (6,000) | 0 | $ (6,000) | 0 |  |
Weighted average future recognition period |  |  |  |  |  |  |  | 2 years 10 months 24 days |  |  |
2021 Equity Incentive Plan [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Exercise of Option |  |  |  |  |  |  |  | 249,144 |  |  |
Stock Issued During Period, Shares, Restricted Stock Award, |  |  |  |  |  |  |  | 99,657 |  |  |
First Seacoast Bank Employee Stock Ownership Plan [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of shares committed to be released each year, ESOP |  |  |  |  |  | 15,354 |  | 15,354 |  |  |
Employee stock option compensation recognized |  |  |  |  |  | $ 32,000 | $ 31,000 | $ 71,000 | $ 62,000 |  |
Unearned compensation for ESOP |  |  |  |  |  | 4,100,000 |  | 4,100,000 |  | 1,900,000 |
Employee stock option unallocated share fair value |  |  |  |  |  | 3,000,000 |  | $ 3,000,000 |  | 1,800,000 |
Employee stock option plan [Member] |  |  |  |  |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Stock repurchase |  |  |  |  |  |  |  | 383,851 |  |  |
Percentage of purchase price common stock |  |  |  |  |  |  |  | 100.00% |  |  |
Remaining principal balance of debt |  |  |  |  |  | $ 4,300,000 |  | $ 4,300,000 |  | $ 2,000,000 |
[1] | Adjusted for conversion of First Seacoast Bancorp, Inc.

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