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Loans and Related Allowance for Loan and Lease Losses - Classes of the Loan Portfolio Summarized by Credit Quality (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Total loans	$ 586,329	$ 533,710	$ 470,584
Commercial And Industrial [Member]
Total loans	59,376	42,536	34,928
Real Estate Construction Porfolio Segment [Member]
Total loans	17,633	22,137	30,296
Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Total loans	258,952	232,478	210,096
Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member]
Total loans	245,636	231,701	190,685
Consumer Portfolio Segment [Member]
Total loans	4,732	4,858	4,579
Pass [Member]
Total loans	570,824	512,697	448,759
Pass [Member] | Commercial And Industrial [Member]
Total loans	57,954	40,560	33,160
Pass [Member] | Real Estate Construction Porfolio Segment [Member]
Total loans	17,448	22,007	29,212
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Total loans	252,783	225,945	200,928
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member]
Total loans	237,916	219,331	180,899
Pass [Member] | Consumer Portfolio Segment [Member]
Total loans	4,723	4,854	4,572
Special Mention [Member]
Total loans	4,163	5,297	4,987
Special Mention [Member] | Commercial And Industrial [Member]
Total loans	445	242
Special Mention [Member] | Real Estate Construction Porfolio Segment [Member]
Total loans	144		495
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Total loans	433	728	584
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member]
Total loans	3,141	4,327	3,908
Substandard [Member]
Total loans	11,325	15,586	16,211
Substandard [Member] | Commercial And Industrial [Member]
Total loans	977	1,734	1,730
Substandard [Member] | Real Estate Construction Porfolio Segment [Member]
Total loans	24
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Total loans	5,736	5,805	8,584
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member]
Total loans	4,579	8,043	5,878
Substandard [Member] | Consumer Portfolio Segment [Member]
Total loans	9	4	7
Doubtful [Member]
Total loans	17	130	627
Doubtful [Member] | Commercial And Industrial [Member]
Total loans			38
Doubtful [Member] | Real Estate Construction Porfolio Segment [Member]
Total loans	17	$ 130	$ 589
Doubtful [Member] | Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member]
Total loans
Doubtful [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member]
Total loans

X

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. 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=65884687&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5074-111524

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