INVESTMENT SECURITIES - Summary of Unrealized Losses - Held-to-Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	$ 0	$ 19,478
Less than 12 months, unrealized loss	0	117
12 months or more, fair value	36,709	12,090
12 months or more, unrealized loss	786	451
Total, fair value	36,709	31,568
Total, unrealized loss	786	568
State, county, and municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	0	6,340
Less than 12 months, unrealized loss	0	22
12 months or more, fair value	1,703	0
12 months or more, unrealized loss	10	0
Total, fair value	1,703	6,340
Total, unrealized loss	10	22
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	0	13,138
Less than 12 months, unrealized loss	0	95
12 months or more, fair value	35,006	12,090
12 months or more, unrealized loss	776	451
Total, fair value	35,006	25,228
Total, unrealized loss	$ 776	$ 546