Securities - Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amortized cost
Total debt securities	$ 498,814	$ 521,337
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	5,655	2,853
Accumulated gross unrealized loss, before tax	(3,861)	(7,327)
Amortized Cost
Securities available for sale	500,608	516,863
U.S. Gov’t sponsored entities
Amortized cost
Total debt securities	129,993	134,010
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	1,127	254
Accumulated gross unrealized loss, before tax	(745)	(1,570)
Amortized Cost
Securities available for sale	130,375	132,694
State & political subdivisions
Amortized cost
Total debt securities	118,673	134,662
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	2,595	1,942
Accumulated gross unrealized loss, before tax	(178)	(573)
Amortized Cost
Securities available for sale	121,090	136,031
Residential & multi-family mortgage
Amortized cost
Total debt securities	207,588	209,126
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	1,711	500
Accumulated gross unrealized loss, before tax	(1,808)	(3,573)
Amortized Cost
Securities available for sale	207,491	206,053
Corporate notes & bonds
Amortized cost
Total debt securities	12,354	12,356
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	26	22
Accumulated gross unrealized loss, before tax	(476)	(601)
Amortized Cost
Securities available for sale	11,904	11,777
Pooled SBA
Amortized cost
Total debt securities	29,186	30,163
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	196	135
Accumulated gross unrealized loss, before tax	(581)	(924)
Amortized Cost
Securities available for sale	28,801	29,374
Other
Amortized cost
Total debt securities	1,020	1,020
Unrealized Gains (Losses)
Accumulated gross unrealized gain, before tax	0	0
Accumulated gross unrealized loss, before tax	(73)	(86)
Amortized Cost
Securities available for sale	$ 947	$ 934