Loans - Summary of Past Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due	$ 626	$ 371
Current	247,078	224,112
Nonaccrual Loans	60	811
Total Loans	247,764	225,294
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due	626	371
Mortgage Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	194,595	174,679
Mortgage Receivable [Member] \| Commercial Real Estate Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due	626
Current	76,458	65,805
Total Loans	77,084	65,805
Mortgage Receivable [Member] \| Commercial Real Estate Mortgage Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due	626
Mortgage Receivable [Member] \| Residential and Home Equity Real Estate Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due		371
Current	94,145	87,850
Nonaccrual Loans		662
Total Loans	94,145	88,883
Mortgage Receivable [Member] \| Residential and Home Equity Real Estate Mortgage Loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Total Past Due		371
Mortgage Receivable [Member] \| Construction Real Estate Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	23,366	19,918
Nonaccrual Loans		73
Total Loans	23,366	19,991
Loans and Finance Receivables [Member] \| Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	46,133	46,264
Nonaccrual Loans	60	76
Total Loans	46,193	46,340
Loans and Finance Receivables [Member] \| Consumer and Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	6,976	4,275
Total Loans	$ 6,976	$ 4,275

Financing receivables that are current.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524

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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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+ References

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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