Derivative Financial Instruments - Summary of Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivatives Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in OCI on Derivative (Effective Portion)	$ (56)	$ 184
Derivatives Designated as Hedging Instruments | Interest rate products | Interest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in OCI on Derivative (Effective Portion)	(56)	184
Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Income	(364)	(306)
Derivatives not designated as hedging instruments | Interest rate lock commitments with customers | Mortgage banking activities, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Income	(28)	680
Derivatives not designated as hedging instruments | Forward sale commitments | Mortgage banking activities, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Income	$ (336)	$ (986)