Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Fair Value, Option, Quantitative Disclosures [Line Items]
Future default rate	3.60%
Period of time with no recovery rate	3 years
Change in fair value discount rate for pooled issue	3.00%
Decrease due to change in applicable discount rate for pooled issue	$ 1,800,000
Increase due to change in applicable discount rate for pooled issue	$ 2,300,000
Change in fair value discount rate for single issue	3.00%
Decrease due to change in applicable discount rate for single issue	$ 900,000
Increase due to change in applicable discount rate for single issue	1,500,000
Transfers within three Levels	0	$ 0
Commercial Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Decrease in fair value of properties	0	0
Consumer Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Decrease in fair value of properties	0	0
Specific Reserve [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans with an aggregate carrying amount	0	0
Charge-offs	0	0
Without Specific Reserve [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans with an aggregate carrying amount	1,700,000	577,000
Without Specific Reserve [Member] \| Loan One [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Charge-offs	53,000	74,000
Without Specific Reserve [Member] \| Loan Two [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Charge-offs	$ 0	$ 0
Pooled Security [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Market spreads	2.75%
Single Issuer [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Market spreads	5.25%

Carrying value of loan impaired.

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Change in fair value discount rate for pooled issue.

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Change in fair value discount rate for single issue.

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Decrease due to change in applicable discount rate for single issue.

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Future default period collateral security.

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Increase due to change in applicable discount ate for pooled issue.

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Increase due to change in applicable discount rate for single issue.

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- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
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Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
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Percentage of likelihood a loan will not be repaid and instead default, used as an input to measure fair value.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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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.

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