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Proposed Business Combination - Additional Information (Detail)			3 Months Ended	9 Months Ended	12 Months Ended
	May 04, 2021 $ / shares shares	May 03, 2021 USD ($) $ / shares	Sep. 30, 2021 USD ($) Office shares	Sep. 30, 2021 USD ($) Office shares	Dec. 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($) shares
Business Acquisition [Line Items]
Common stock shares outstanding | shares			12,230,000	12,230,000	12,230,000
Business combination, acquisition related costs			$ 1,200,000	$ 2,100,000	$ 42,500
Consulting Fees [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs			10,300	255,200	12,500
Other General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs			61,500	$ 241,300	$ 30,000.0
Perpetual Federal Savings Bank {Member]
Business Acquisition [Line Items]
Business acquisition, date of acquisition agreement				May 04, 2021
Assets						$ 391,000,000
Loans						326,000,000
Deposits						305,000,000
Tangible equity						$ 79,000,000
Business acquisition, expected closing date	Oct. 01, 2021
Aggregate cash consideration		$ 103,700,000
Stock issuable to PFSB | shares	1,776
Cash payment for exchange of each share | $ / shares	$ 41.20
Common stock shares outstanding | shares						2,470,032
Share price | $ / shares		$ 24.22
Business acquisition subjected to adjustment based upon shares issued in merger | shares	1,833,999
Business combination, acquisition related costs			275,400	$ 523,500
Perpetual Federal Savings Bank {Member] | Consulting Fees [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs			69,000.0	160,800
Perpetual Federal Savings Bank {Member] | Other General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs			$ 206,300	$ 362,700
Perpetual Federal Savings Bank {Member] | Urbana Ohio [Member]
Business Acquisition [Line Items]
Number of full-service offices | Office			1	1

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Date when the business acquisition agreement was executed, in YYYY-MM-DD format.

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Number of shares of equity interests issued or issuable to acquire entity.

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