Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Amortized Cost
Less than one year	$ 69,635
Due after one year through five years	203,081
Due after five years through ten years	71,590
Due after ten years	13,800
Total Amortized Cost	358,106
Estimated Fair Value
Less than one year	69,723
Due after one year through five years	205,520
Due after five years through ten years	70,118
Due after ten years	13,815
Total Estimated Fair Value	$ 359,176