Summary of Significant Accounting Policies - Additional Information (Detail)			3 Months Ended		9 Months Ended
	Jan. 19, 2023 $ / shares shares	Aug. 17, 2021 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Segment Service $ / shares shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares
Common stock, price per share | $ / shares			$ 0.01		$ 0.01		$ 0.01
Common stock issued | shares			5,192,612		5,192,612		5,192,612
Number of core services | Service					4
Number of reportable segment | Segment					1
Accounts purchase price | $		$ 324,000
Deposit assets, amortization expense from expirations | $			$ 8,000	$ 8,000	$ 24,000	$ 22,000
Emerging growth of company status					(i) the last day of the fiscal year of the Company during which it had total annual gross revenues of $1.235 billion (as adjusted for inflation) or more; (ii) the last day of the fiscal year of the Company following the fifth anniversary of the effective date of the Company’s initial public offering (which will be December 31, 2024 for the Company); (iii) the date on which the Company has, during the previous three-year period, issued more than $1.0 billion in non-convertible debt; or (iv) the date on which the Company is deemed to be a “large accelerated filer” under Securities and Exchange Commission regulations (generally, at least $700 million of voting and non-voting equity held by non-affiliates).
Customer List Intangible [Member]
Intangible balances | $			$ 223,000		$ 223,000		$ 247,000
First Seacoast Bancorp, Inc [Member]
Common stock shares sold | shares	2,805,000
Common stock, price per share | $ / shares	$ 10
Common stock coversion ratio	0.8358
First Seacoast Bancorp, Inc [Member] | First Seacoast Bank Employee Stock Ownership Plan [Member]
Common stock issued | shares	224,400