INVESTMENT SECURITIES - Schedule of Unrealized Losses and Fair Value by Investment Category for Securities Held to Maturity (Detail) $ in Thousands	Sep. 30, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Schedule of Held-to-maturity Securities [Line Items]
Count | Security	17	7
Less than 12 months, fair value	$ 14,440	$ 7,608
Less than 12 months, unrealized losses	(215)	(18)
12 months or more, fair value	2,251	2,522
12 months or more, unrealized losses	(124)	(45)
Total, fair value	16,691	10,130
Total, unrealized losses	$ (339)	$ (63)
Obligations of state and political subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Count | Security	8	1
Less than 12 months, fair value	$ 11,422	$ 6,007
Less than 12 months, unrealized losses	(109)	(15)
12 months or more, fair value	0	0
12 months or more, unrealized losses	0	0
Total, fair value	11,422	6,007
Total, unrealized losses	$ (109)	$ (15)
Residential mortgage-backed securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Count | Security	9	6
Less than 12 months, fair value	$ 3,018	$ 1,601
Less than 12 months, unrealized losses	(106)	(3)
12 months or more, fair value	2,251	2,522
12 months or more, unrealized losses	(124)	(45)
Total, fair value	5,269	4,123
Total, unrealized losses	$ (230)	$ (48)