Securities - Schedule of Contractual Maturity of Securities Available for Sale, Excluding Equity Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost
1 year or less	$ 59,815
1 year – 5 years	104,134
5 years – 10 years	66,534
After 10 years	4,253
Total, Amortized Cost	234,736
Amortized cost	533,203	$ 521,337
Fair Value
1 year or less	59,831
1 year – 5 years	106,084
5 years – 10 years	70,191
After 10 years	4,397
Total, Fair Value	240,503
Securities available for sale	542,313	516,863
Residential & multi-family mortgage
Amortized Cost
Mortgage & asset backed securities, Amortized Cost	273,404
Amortized cost	273,404	209,126
Fair Value
Mortgage & asset backed securities, Fair Value	276,636
Securities available for sale	276,636	206,053
Pooled SBA
Amortized Cost
Mortgage & asset backed securities, Amortized Cost	25,063
Amortized cost	25,063	30,163
Fair Value
Mortgage & asset backed securities, Fair Value	25,174
Securities available for sale	$ 25,174	$ 29,374