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Loans and Related Allowance for Loan and Lease Losses - Additional Information on Impaired Loans (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Average Recorded Investment | $ 13,302 | $ 13,504 | $ 13,737 | $ 13,359 | $ 13,440 | $ 16,960 | $ 17,824
Interest Income Recognized | 51 | 163 | 182 | 495 | 725 | 640 | 1,090
Commercial And Industrial [Member] |  |  |  |  |  |  |
Average Recorded Investment | 864 | 1,480 | 1,218 | 1,354 | 1,468 | 1,989 | 2,187
Interest Income Recognized | 4 | 21 | 9 | 73 | 100 | 85 | 119
Real Estate Construction Porfolio Segment [Member] |  |  |  |  |  |  |
Average Recorded Investment | 1,105 | 2,347 | 1,404 | 2,614 | 2,407 | 3,631 | 3,743
Interest Income Recognized | 3 | 28 | 22 | 94 | 115 | 154 | 183
Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member] |  |  |  |  |  |  |
Average Recorded Investment | 3,389 | 4,195 | 3,660 | 4,514 | 4,356 | 5,331 | 5,380
Interest Income Recognized | 36 | 43 | 36 | 128 | 160 | 171 | 293
Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member] |  |  |  |  |  |  |
Average Recorded Investment | 7,939 | 5,476 | 7,449 | 4,871 | 5,203 | 5,998 | 6,500
Interest Income Recognized | 8 | 71 | 115 | 200 | 350 | 229 | 493
Consumer Portfolio Segment [Member] |  |  |  |  |  |  |
Average Recorded Investment | 5 | $ 6 | 6 | $ 6 | $ 6 | 11 | 13
Interest Income Recognized |  |  |  |  |  | $ 1 | $ 1

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- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524 + Details
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- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524 + Details
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