Securities - Securities with Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Less than 12 Months
Fair Value	$ 98,395	$ 106,735
Unrealized Loss	(766)	(771)
12 Months or More
Fair Value	210,530	134,831
Unrealized Loss	(6,561)	(3,428)
Fair Value	308,925	241,566
Unrealized Loss	(7,327)	(4,199)
U.S. Gov’t sponsored entities
Less than 12 Months
Fair Value	14,786	55,696
Unrealized Loss	(41)	(540)
12 Months or More
Fair Value	70,676	34,754
Unrealized Loss	(1,529)	(368)
Fair Value	85,462	90,450
Unrealized Loss	(1,570)	(908)
State & political subdivisions
Less than 12 Months
Fair Value	13,834	15,890
Unrealized Loss	(62)	(69)
12 Months or More
Fair Value	21,080	4,104
Unrealized Loss	(511)	(245)
Fair Value	34,914	19,994
Unrealized Loss	(573)	(314)
Residential & multi-family mortgage
Less than 12 Months
Fair Value	69,015	30,144
Unrealized Loss	(656)	(153)
12 Months or More
Fair Value	87,286	63,699
Unrealized Loss	(2,917)	(1,729)
Fair Value	156,301	93,843
Unrealized Loss	(3,573)	(1,882)
Corporate notes & bonds
Less than 12 Months
Fair Value	0	5,005
Unrealized Loss	0	(9)
12 Months or More
Fair Value	9,759	9,042
Unrealized Loss	(601)	(453)
Fair Value	9,759	14,047
Unrealized Loss	(601)	(462)
Pooled SBA
Less than 12 Months
Fair Value	760	0
Unrealized Loss	(7)	0
12 Months or More
Fair Value	20,795	22,270
Unrealized Loss	(917)	(575)
Fair Value	21,555	22,270
Unrealized Loss	(924)	(575)
Other
Less than 12 Months
Fair Value	0	0
Unrealized Loss	0	0
12 Months or More
Fair Value	934	962
Unrealized Loss	(86)	(58)
Fair Value	934	962
Unrealized Loss	$ (86)	$ (58)