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Securities - Summary of Investments in an Unrealized Loss Position that were Temporarily Impaired (Detail) (USD $) In Thousands, unless otherwise specified | Sep. 30, 2014 | Dec. 31, 2013
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Summary of investments in unrealized loss position that were temporarily impaired |  |
Less than 12 months - Fair Value | $ 17,449 | $ 56,975
12 months or more - Fair Value | 39,700 | 12,843
Total - Fair Value | 57,149 | 69,818
Summary of investments in unrealized loss position that were temporarily impaired, Unrealized (Loss) |  |
Less than 12 months - Unrealized (Loss) | (210) | (2,177)
12 months or more - Unrealized (Loss) | (1,210) | (559)
Total Unrealized (Loss) | (1,420) | (2,736)
U.S. Agency and Mortgage-Backed Securities [Member] |  |
Summary of investments in unrealized loss position that were temporarily impaired |  |
Less than 12 months - Fair Value | 15,817 | 49,810
12 months or more - Fair Value | 33,557 | 10,180
Total - Fair Value | 49,374 | 59,990
Summary of investments in unrealized loss position that were temporarily impaired, Unrealized (Loss) |  |
Less than 12 months - Unrealized (Loss) | (205) | (1,755)
12 months or more - Unrealized (Loss) | (1,043) | (383)
Total Unrealized (Loss) | (1,248) | (2,138)
Obligations of States and Political Subdivisions [Member] |  |
Summary of investments in unrealized loss position that were temporarily impaired |  |
Less than 12 months - Fair Value | 1,632 | 7,165
12 months or more - Fair Value | 6,143 | 2,663
Total - Fair Value | 7,775 | 9,828
Summary of investments in unrealized loss position that were temporarily impaired, Unrealized (Loss) |  |
Less than 12 months - Unrealized (Loss) | (5) | (422)
12 months or more - Unrealized (Loss) | (167) | (176)
Total Unrealized (Loss) | $ (172) | $ (598)

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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are 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 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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