Business Combination and Asset Purchase - Additional Information (Detail)				3 Months Ended	6 Months Ended		12 Months Ended
	Apr. 30, 2021 USD ($) Office $ / shares shares	Nov. 16, 2020 USD ($) shares	Jan. 01, 2019 USD ($) Office $ / shares shares	Jun. 30, 2021 USD ($) shares	Jun. 30, 2021 USD ($) shares	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) shares	Nov. 30, 2020 USD ($) Client
Business Acquisition [Line Items]
Common stock, shares outstanding | shares				12,230,000	12,230,000		12,230,000
Business combination, acquisition related costs				$ 977,500	$ 977,500		$ 42,500
Recognition of core deposit intangible asset with acquired purchase					$ 3,900,000
Remaining economic useful life					7 years
Goodwill				56,066,000	$ 56,066,000		47,340,000
Goodwill deductible for tax purpose, period	15 years
Fair value of assets acquired				52,400,000	52,400,000
Gross principal and contractual interest				58,600,000	58,600,000
Acquisition expected to be uncollectible				1,100,000	$ 1,100,000
Loan receivable weighted average life					52 months
Business combination, premises and equipment written down value					$ 596,000
Business combination, average remaining life					39 years
Fair value for certificate of deposit, valuation amount				59,000	$ 59,000
Fair value for certificate of deposit, amortization period					1 year 4 months 24 days
Pro-forma operating revenue, net of tax				232,000
Amortization expense					$ 303,000	$ 364,000
Amortization expense for 2021				653,000	653,000	653,000
Custar [Member]
Business Acquisition [Line Items]
Amortization expense						84,000
Building
Business Acquisition [Line Items]
Business combination, premises and equipment written down value					244,000
Customer Lists [Member]
Business Acquisition [Line Items]
Amortization expense					61,000
Amortization expense for 2021				123,000	123,000
Other General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs				179,800	179,800		30,000.0
Consulting Fees [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs				245,000.0	245,000.0		$ 12,500
Employee Benefits [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs				541,500	541,500
ATM Expense [Member]
Business Acquisition [Line Items]
Business combination, acquisition related costs				11,200	11,200
Ossian State Bank [Member]
Business Acquisition [Line Items]
Number of full-service offices | Office	2
Ossian Financial Services, Inc. [Member]
Business Acquisition [Line Items]
Cash payment for exchange of each share | $ / shares	$ 67.71
Common stock, shares outstanding | shares	295,388
Total consideration for acquisition	$ 20,001,000
Goodwill	8,726,000
Cash paid for the capital stock	20,001,000				20,001,000
Amortization expense for 2021						$ 93,000
Ossian Financial Services, Inc. [Member] | Core Deposits [Member]
Business Acquisition [Line Items]
Recognition of core deposit intangible asset with acquired purchase	$ 980,200
Remaining economic useful life	7 years
Bank of Geneva [Member]
Business Acquisition [Line Items]
Number of full-service offices | Office			6
Limberlost Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Cash payment for exchange of each share | $ / shares			$ 8,465.00
Common stock, shares outstanding | shares			1,000
Total consideration for acquisition			$ 78,900,000
Goodwill			$ 43,300,000
Common stock issued in exchange of each outstanding share | shares			1,830,000
Share price | $ / shares			$ 38.49
Cash paid for the capital stock			$ 8,500,000
Stock issued for acquisition			70,400,000
Limberlost Bancshares, Inc. [Member] | Core Deposits [Member]
Business Acquisition [Line Items]
Recognition of core deposit intangible asset with acquired purchase			$ 3,900,000
Remaining economic useful life			7 years
Adams County Financial Resources
Business Acquisition [Line Items]
Total consideration for acquisition		$ 825,000
Common stock issued in exchange of each outstanding share | shares		40,049
Stock issued for acquisition		$ 825,000
Assets under management amount								$ 83,000,000
Number of clients assets under management | Client								450
Increase to noninterest income		500,000
Adams County Financial Resources | Customer Lists [Member]
Business Acquisition [Line Items]
Recognition of core deposit intangible asset with acquired purchase		$ 800,000
Remaining economic useful life		6 years 6 months
Amortization expense for 2021				$ 123,000	$ 123,000