Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax effect	$ (1,119)	$ 2,167
Total accumulated other comprehensive income (loss)	4,207	(8,144)
Unrealized gain (loss) on securities available for sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), before tax	10,151	(8,561)
Unamortized gain (loss) on securities held to maturity, previously transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), before tax	(58)	10
Unrealized loss on derivative instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), before tax	$ (4,767)	$ (1,760)