Business Combination and Asset Purchase - Summary of Changes in Accretable Yield or Income Expected to be Collected (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Peoples Federal Savings and Loan [Member]
Business Acquisition [Line Items]
Beginning Balance	$ 680		$ 798
Additions	2		6
Accretion	(58)		(174)
Disposals			(6)
Ending Balance	624		624		$ 798
Perpetual Federal Savings Bank [Member]
Business Acquisition [Line Items]
Beginning Balance	3,572	$ 4,710	4,236	$ 5,262	5,262
Additions	14	28	39	125
Accretion	(456)	(330)	(1,145)	(979)
Disposals		(2)		(2)
Ending Balance	3,130	4,406	3,130	4,406	4,236
Ossian Financial Services, Inc. [Member]
Business Acquisition [Line Items]
Beginning Balance	382	557	470	645	645
Additions		1		1
Accretion	(44)	(44)	(132)	(132)
Ending Balance	338	514	338	514	470
Limberlost Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Beginning Balance	575	994	785	1,198	1,198
Additions	6	2	11	10
Accretion	(109)	(107)	(324)	(319)
Ending Balance	$ 472	$ 889	$ 472	$ 889	$ 785

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479907/805-20-50-5

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The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481906/310-30-15-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481696/310-30-50-2

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Current period recognition due to accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Increases in the aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan due to the acquisition of similar loans accounted for as debt securities during the period. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Sale or transfer of a loan during the period resulting in a reduction in the excess of a loan's cash flows expected to be collected over the investor's initial investment. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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