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Loans and Related Allowance for Loan and Lease Losses - Major Classifications of Net Loans (Detail) - USD ($) $ in Thousands | Sep. 30, 2016 | Jun. 30, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
--- | --- | --- | --- | --- | --- | --- | --- | ---
Financing Receivable Gross | $ 586,329 |  | $ 533,710 |  |  | $ 470,584 |  |
Less: Allowance for loan and lease losses | 6,334 | $ 6,366 | 6,385 | $ 6,320 | $ 6,346 | 6,846 | $ 7,046 | $ 7,779
Net loans | 579,995 |  | 527,325 |  |  | 463,738 |  |
Commercial And Industrial [Member] |  |  |  |  |  |  |  |
Financing Receivable Gross | 59,376 |  | 42,536 |  |  | 34,928 |  |
Less: Allowance for loan and lease losses | 513 | 484 | 867 | 578 | 610 | 642 | 614 | 1,732
Real Estate Construction Porfolio Segment [Member] |  |  |  |  |  |  |  |
Financing Receivable Gross | 17,633 |  | 22,137 |  |  | 30,296 |  |
Less: Allowance for loan and lease losses | 138 | 159 | 276 | 334 | 363 | 868 | 576 | 1,123
Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member] |  |  |  |  |  |  |  |
Financing Receivable Gross | 258,952 |  | 232,478 |  |  | 210,096 |  |
Less: Allowance for loan and lease losses | 2,761 | 2,788 | 3,139 | 3,426 | 3,347 | 3,703 | 3,664 | 2,872
Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member] |  |  |  |  |  |  |  |
Financing Receivable Gross | 245,636 |  | 231,701 |  |  | 190,685 |  |
Less: Allowance for loan and lease losses | 2,895 | 2,909 | 2,078 | 1,939 | 1,978 | 1,576 | 2,170 | 1,991
Consumer Portfolio Segment [Member] |  |  |  |  |  |  |  |
Financing Receivable Gross | 4,732 |  | 4,858 |  |  | 4,579 |  |
Less: Allowance for loan and lease losses | $ 27 | $ 26 | $ 25 | $ 43 | $ 48 | $ 57 | $ 22 | $ 61

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- Definition Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for 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 50 -Paragraph 11B -Subparagraph (g) -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 -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.1) -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544 + Details
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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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- Definition Amount after allowance and 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 and loans held for sale. + 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 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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