Investment securities - Schedule of Investment Securities (Detail)	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	$ 8,696,093
Debt Securities, Available-for-sale, Total	8,635,077
Investment Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	8,696,093
Gross unrealized gains	0
Gross unrealized losses	(61,016)
Debt Securities, Available-for-sale, Total	8,635,077
Federal agency bonds — mortgage-backed
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	8,696,093
Gross unrealized gains	0
Gross unrealized losses	(61,016)
Debt Securities, Available-for-sale, Total	$ 8,635,077

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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