Investment Securities - Reconciliation of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 115,752	$ 123,975
Gross Unrealized Gains	3,271	1,115
Gross Unrealized Losses	0	(186)
Fair Value	119,023	124,904
U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	31,207	31,335
Gross Unrealized Gains	901	182
Gross Unrealized Losses	0	(8)
Fair Value	32,108	31,509
Mortgage-backed securities, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	70,999	76,229
Gross Unrealized Gains	2,162	734
Gross Unrealized Losses	0	(176)
Fair Value	73,161	76,787
Mortgage-backed securities, multifamily
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	740	1,750
Gross Unrealized Gains	44	4
Gross Unrealized Losses	0	(2)
Fair Value	784	1,752
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,306	12,161
Gross Unrealized Gains	164	195
Gross Unrealized Losses	0	0
Fair Value	10,470	12,356
Debt securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,500	2,500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 2,500	$ 2,500