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Short-term Borrowings (Details) - Outstanding Balances and Related Information of Short-term Borrowings (Detail) - USD ($) $ in Thousands | 12 Months Ended |
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Dec. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2016
Outstanding Balances and Related Information of Short-term Borrowings [Abstract] |  |  |
Balance at year-end | $ 35,825 | $ 14,808 | $ 32,803
Average balance outstanding | 11,768 | 8,379 |
Maximum month-end balance | $ 35,825 | $ 19,970 |
Weighted-average rate at year-end | 1.37% | 0.98% |
Weighted-average rate during the year | 1.65% | 1.77% |

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- Definition Outstanding Balances And Related Information Of Short Term Borrowings [Abstract] + References No definition available. + Details
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- Definition The average effective interest rate during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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