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Securities - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2016 USD ($) Securities Obligation | Dec. 31, 2015 USD ($) Securities Obligation
Amortized Cost and Fair Value Debt Securities [Abstract] |  |
Number of U.S. agency and mortgage-backed securities | Securities | 64 | 52
Number of obligations of state and political subdivisions in an unrealized loss position | Obligation | 50 | 13
Percentage of investment portfolio | 100.00% | 100.00%
Weighted-average period of re-pricing of portfolio | 4 years 8 months 12 days | 4 years 7 months 6 days
Number of corporate debt security | Securities | 1 |
Proceeds from maturities, calls, principal payments and sales of securities available for sale | $ 22,826,000 | $ 17,725,000
Gross realized gains on securities available for sale | 22,000 | 0
Gross realized losses on securities available for sale | 14,000 | 55,000
Proceeds from sales of securities held to maturity | 657,000 |
Proceeds from maturities, calls and principal payments of securities held to maturity | 12,821,000 | 2,341,000
Gross gains or losses on held to maturity securities | 0 | 0
Securities book value | 27,700,000 | $ 26,900,000
Impairment recognized | $ 0 |

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- Definition Impairment losses related to federal home loan stock. + References No definition available. + Details
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- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 + Details
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- Definition The carrying amount of securities categorized neither as held-to-maturity nor trading which serve as security for borrowings or other arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(f)) -URI http://asc.fasb.org/extlink&oid=6488002&loc=d3e600178-122990 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX210.4-08(b)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 4: 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(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5086-111524 + Details
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