Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Amortized Cost
Less than one year, Amortized Cost	$ 70,039
Due after one year through five years, Amortized Cost	185,985
Due after five years through ten years, Amortized Cost	90,088
Due after ten years, Amortized Cost	14,297
Total Amortized Cost	360,409
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Less than one year, Estimated Fair Value	69,999
Due after one year through five years, Estimated Fair Value	187,643
Due after five years through ten years, Estimated Fair Value	87,249
Due after ten years, Estimated Fair Value	14,918
Total Estimated Fair Value	$ 359,809

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.

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