Securities - Schedule of Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands |
Sep. 30, 2018 |
Dec. 31, 2017 |
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| Investments, Debt and Equity Securities [Abstract] | ||
| Available-for-Sale Within one year, Amortized Cost | $ 18,067 | |
| Available-for-Sale Over one year through five years, Amortized Cost | 116,744 | |
| Available-for-Sale Over five years through ten years, Amortized Cost | 228,679 | |
| Available-for-Sale Over ten years, Amortized Cost | 224,607 | |
| Amortized Cost | 588,097 | $ 581,992 |
| Available-for-Sale Within one year, Estimated Fair Value | 18,027 | |
| Available-for-Sale Over one year through five years, Estimated Fair Value | 114,401 | |
| Available-for-Sale Over five years through ten years, Estimated Fair Value | 222,171 | |
| Available-for-Sale Over ten years, Estimated Fair Value | 217,637 | |
| Estimated fair value | $ 572,236 | $ 578,804 |
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amortized cost of investment in debt security measured at fair value with change recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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