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Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2014 | Dec. 31, 2013
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Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Losses, Less Than Twelve Months | $ (4,142) | $ (4,611)
Fair Value, Less Than Twelve Months | 160,645 | 164,278
Gross Unrealized Losses, Twelve Months and Over | (376) | (403)
Fair Value, Twelve Months and Over | 5,035 | 4,598
U.S. Treasury [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Losses, Less Than Twelve Months | (780) | (795)
Fair Value, Less Than Twelve Months | 25,229 | 25,272
Gross Unrealized Losses, Twelve Months and Over |  |
Fair Value, Twelve Months and Over |  |
U.S. Government agency [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Losses, Less Than Twelve Months | (2,412) | (2,783)
Fair Value, Less Than Twelve Months | 92,561 | 96,241
Gross Unrealized Losses, Twelve Months and Over | (355) | (403)
Fair Value, Twelve Months and Over | 4,646 | 4,598
Mortgage-backed securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Losses, Less Than Twelve Months | (324) | (574)
Fair Value, Less Than Twelve Months | 20,008 | 23,171
Gross Unrealized Losses, Twelve Months and Over |  |
Fair Value, Twelve Months and Over |  |
State and local governments [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Losses, Less Than Twelve Months | (626) | (459)
Fair Value, Less Than Twelve Months | 22,847 | 19,594
Gross Unrealized Losses, Twelve Months and Over | (21) |
Fair Value, Twelve Months and Over | $ 389 |

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- Definition Amount of accumulated pre-tax unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months impacting investments. + References No definition available. + Details
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- Definition Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Aggregate Losses Accumulated In Investments + References No definition available. + 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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