Investment Securities - Reconciliation of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 123,975	$ 153,646
Gross Unrealized Gains	1,115	282
Gross Unrealized Losses	(186)	(2,996)
Investment securities held to maturity, Fair Value	124,904	150,932
U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	31,335	33,025
Gross Unrealized Gains	182	0
Gross Unrealized Losses	(8)	(677)
Investment securities held to maturity, Fair Value	31,509	32,348
Mortgage-backed securities, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	76,229	75,859
Gross Unrealized Gains	734	169
Gross Unrealized Losses	(176)	(1,838)
Investment securities held to maturity, Fair Value	76,787	74,190
Mortgage-backed securities, multifamily
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,750	1,853
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(2)	(35)
Investment securities held to maturity, Fair Value	1,752	1,818
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,161	37,909
Gross Unrealized Gains	195	113
Gross Unrealized Losses	0	(328)
Investment securities held to maturity, Fair Value	12,356	37,694
Debt securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,500	5,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(118)
Investment securities held to maturity, Fair Value	$ 2,500	$ 4,882