Loans (Impaired Loans) - Additional Information (Detail)	3 Months Ended	12 Months Ended
Mar. 31, 2020 USD ($) Contract Loan	Mar. 31, 2019 USD ($) Loan	Dec. 31, 2019 USD ($) Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additional funds available to be advanced in connection with impaired loans	$ 45,000
Impaired loans classified as troubled debt restructured	$ 1,900,000	$ 173,000	$ 1,000,000
Number of contracts modified \| Loan	2		0
TDR loans, subsequently defaulted during the period	0	0
TDR impaired loans paid off \| Loan	1	0
Maximum time for re-evaluation (in months)	12 months
Re-evaluation period for real estate	2 years
Unsecured consumer loans, credit card credits and overdraft lines of credit reach	90 days
Delinquent period for charging down consumer loans	120 days
Delinquent period for charging down commercial and agricultural credits	120 days
Foreclosed residential real estate property	$ 185,000		$ 214,000
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Foreclosed residential real estate property	50,000	$ 0
Residential real estate properties foreclosure proceedings	$ 292,000	$ 639,000
Principal Forgiveness [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of contracts modified \| Contract	0
Payment Changes from Monthly Payment to Principal and Interest at Maturity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of contracts modified \| Contract	2
Loan maturity date	Jun. 19, 2020

Additional funds available to be advanced in connection with impaired loans.

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Delinquent period for charging down commercial and agricultural credits.

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Delinquent period for charging down consumer loans

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Financing receivables impaired number of troubled debt restructuring write down.

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Maximum time for reevaluation.

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Re evaluation period for real estate.

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- Definition

Unsecured consumer loans credit card credits and overdraft.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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Number of financing receivables that have been modified by troubled debt restructurings.

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Amount of financing receivable modified as troubled debt restructuring.

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Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

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- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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