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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 |  |  |

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- 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 + Details
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