Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 |
In Thousands, unless otherwise specified |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | $282,691 | $257,770 |
Equity securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 3,682 | 9,302 |
Other Investments [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 10,820 | 10,591 |
Fair Value, Measurements, Recurring [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 282,691 | 257,770 |
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 268,189 | 237,877 |
Fair Value, Measurements, Recurring [Member] | Other Investments [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 10,820 | 10,591 |
Fair Value, Measurements, Recurring [Member] | Common Stock | Equity securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 3,682 | 9,302 |
Fair Value, Measurements, Recurring [Member] | States and political subdivisions [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 154,075 | 150,375 |
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 107,094 | 80,428 |
Fair Value, Measurements, Recurring [Member] | U.S. agency-based mortgage-backed securities [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 7,020 | 7,074 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 3,682 | 9,302 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common Stock | Equity securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 3,682 | 9,302 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | States and political subdivisions [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. agency-based mortgage-backed securities [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 268,189 | 237,877 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 268,189 | 237,877 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common Stock | Equity securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | States and political subdivisions [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 154,075 | 150,375 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 107,094 | 80,428 |
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. agency-based mortgage-backed securities [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 7,020 | 7,074 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 10,820 | 10,591 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | 10,820 | 10,591 |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common Stock | Equity securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | States and political subdivisions [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | U.S. agency-based mortgage-backed securities [Member] | Debt Securities [Member] | ' | ' |
Fair Value Measurements Disclosure [Line Items] | ' | ' |
Securities available for sale/Available-for-sale, Fair value | ' | ' |