INVESTMENT SECURITIES - Schedule of Unrealized Losses and Fair Value by Investment Category for Securities Available for Sale (Detail) $ in Thousands	Jun. 30, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Count | Security	410
Count | Security		331
Less than 12 months fair value	$ 152,647
Less than 12 months, fair value		$ 121,584
Less than 12 Months unrealized losses	(3,255)
Less than 12 months unrealized losses		(1,268)
12 months or more fair value	68,349
12 months or more, fair value		57,812
12 months or more unrealized losses	(2,684)
12 months or more unrealized losses		(1,550)
Total fair value	220,996
Total Fair Value		179,396
Total unrealized losses	$ (5,939)
Unrealized losses		$ (2,818)
Obligations of U.S. government agencies and corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	18
Count | Security		14
Less than 12 months fair value	$ 7,167
Less than 12 months, fair value		$ 5,815
Less than 12 Months unrealized losses	(131)
Less than 12 months unrealized losses		(50)
12 months or more fair value	1,751
12 months or more, fair value		1,505
12 months or more unrealized losses	(68)
12 months or more unrealized losses		(31)
Total fair value	8,918
Total Fair Value		7,320
Total unrealized losses	$ (199)
Unrealized losses		$ (81)
Obligations of state and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	63
Count | Security		57
Less than 12 months fair value	$ 23,093
Less than 12 months, fair value		$ 12,315
Less than 12 Months unrealized losses	(404)
Less than 12 months unrealized losses		(77)
12 months or more fair value	9,863
12 months or more, fair value		9,930
12 months or more unrealized losses	(398)
12 months or more unrealized losses		(345)
Total fair value	32,956
Total Fair Value		22,245
Total unrealized losses	$ (802)
Unrealized losses		$ (422)
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	28
Count | Security		20
Less than 12 months fair value	$ 6,896
Less than 12 months, fair value		$ 1,116
Less than 12 Months unrealized losses	(70)
Less than 12 months unrealized losses		(6)
12 months or more fair value	5,835
12 months or more, fair value		6,273
12 months or more unrealized losses	(412)
12 months or more unrealized losses		(324)
Total fair value	12,731
Total Fair Value		7,389
Total unrealized losses	$ (482)
Unrealized losses		$ (330)
Residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	206
Count | Security		159
Less than 12 months fair value	$ 86,094
Less than 12 months, fair value		$ 71,893
Less than 12 Months unrealized losses	(1,945)
Less than 12 months unrealized losses		(729)
12 months or more fair value	31,571
12 months or more, fair value		28,410
12 months or more unrealized losses	(1,179)
12 months or more unrealized losses		(541)
Total fair value	117,665
Total Fair Value		100,303
Total unrealized losses	$ (3,124)
Unrealized losses		$ (1,270)
Commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	95
Count | Security		80
Less than 12 months fair value	$ 29,397
Less than 12 months, fair value		$ 30,445
Less than 12 Months unrealized losses	(705)
Less than 12 months unrealized losses		(406)
12 months or more fair value	19,329
12 months or more, fair value		11,216
12 months or more unrealized losses	(627)
12 months or more unrealized losses		(280)
Total fair value	48,726
Total Fair Value		41,661
Total unrealized losses	$ (1,332)
Unrealized losses		$ (686)
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security		1
Less than 12 months, fair value		$ 0
Less than 12 months unrealized losses		0
12 months or more, fair value		478
12 months or more unrealized losses		(29)
Total Fair Value		478
Unrealized losses		$ (29)