Securities - Schedule of Contractual Maturity of Securities Available for Sale, Excluding Equity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Amortized Cost
1 year or less	$ 76,122
1 year – 5 years	113,884
5 years – 10 years	71,326
After 10 years	5,395
Total, Amortized Cost	266,727
Total debt securities	525,343	$ 521,337
Fair Value
1 year or less	75,987
1 year – 5 years	115,445
5 years – 10 years	75,086
After 10 years	5,552
Total, Fair Value	272,070
Total debt securities	533,970	516,863
Residential and multi-family mortgage
Amortized Cost
Mortgage & asset backed securities, Amortized Cost	229,925
Fair Value
Mortgage & asset backed securities, Fair Value	233,064
Pooled SBA
Amortized Cost
Mortgage & asset backed securities, Amortized Cost	27,671
Total debt securities	27,671	30,163
Fair Value
Mortgage & asset backed securities, Fair Value	27,876
Total debt securities	27,876	29,374
Other
Amortized Cost
Mortgage & asset backed securities, Amortized Cost	1,020
Total debt securities	1,020	1,020
Fair Value
Mortgage & asset backed securities, Fair Value	960
Total debt securities	$ 960	$ 934