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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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