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Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest-bearing deposits maturing date	90 days
Transfer of assets into or out of level 3	$ 0	$ 0
Transfer of liabilities into or out of level 3	0	0
Collateral dependent impaired loans categorized as Level 3	2,054,000	1,745,000
Specific allocation for collateral dependent impaired loans	31,000	106,000
Asset impairment charges	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans categorized as Level 3	$ 215,000	$ 508,000

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Maximum maturity period of carrying amount interest bearing deposits.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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-Publisher FASB
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-Section 50
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