INVESTMENT SECURITIES - Schedule of Unrealized Losses and Fair Value by Investment Category for Securities Available for Sale (Detail) $ in Thousands	Sep. 30, 2017 USD ($) Security	Dec. 31, 2016 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Count | Security	251	222
Less than 12 months fair value	$ 139,053	$ 115,234
Less than 12 Months unrealized losses	(1,134)	(3,268)
12 months or more fair value	23,259	9,647
12 months or more unrealized losses	(689)	(315)
Total fair value	162,312	124,881
Unrealized losses	$ (1,823)	$ (3,583)
Obligations of other U.S. government agencies and corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	73	45
Less than 12 months fair value	$ 39,719	$ 22,819
Less than 12 Months unrealized losses	(351)	(382)
12 months or more fair value	1,162	448
12 months or more unrealized losses	(19)	(5)
Total fair value	40,881	23,267
Unrealized losses	$ (370)	$ (387)
Obligations of state and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	24	33
Less than 12 months fair value	$ 16,960	$ 25,764
Less than 12 Months unrealized losses	(73)	(1,791)
12 months or more fair value	9,367	0
12 months or more unrealized losses	(315)	0
Total fair value	26,327	25,764
Unrealized losses	$ (388)	$ (1,791)
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	23	27
Less than 12 months fair value	$ 3,002	$ 3,724
Less than 12 Months unrealized losses	(63)	(132)
12 months or more fair value	7,652	6,929
12 months or more unrealized losses	(268)	(246)
Total fair value	10,654	10,653
Unrealized losses	$ (331)	$ (378)
Residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	124	110
Less than 12 months fair value	$ 77,167	$ 60,433
Less than 12 Months unrealized losses	(597)	(883)
12 months or more fair value	4,397	1,778
12 months or more unrealized losses	(57)	(17)
Total fair value	81,564	62,211
Unrealized losses	$ (654)	$ (900)
Commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	4	4
Less than 12 months fair value	$ 1,960	$ 2,444
Less than 12 Months unrealized losses	(41)	(76)
12 months or more fair value	200	0
12 months or more unrealized losses	(5)	0
Total fair value	2,160	2,444
Unrealized losses	$ (46)	$ (76)
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Count | Security	3	3
Less than 12 months fair value	$ 245	$ 50
Less than 12 Months unrealized losses	(9)	(4)
12 months or more fair value	481	492
12 months or more unrealized losses	(25)	(47)
Total fair value	726	542
Unrealized losses	$ (34)	$ (51)