INVESTMENT SECURITIES - Schedule of Gross Unrealized Losses and Fair Value of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Estimated Fair Value
Less Than 12 Months	$ 131,176	$ 160,820
12 Months or More	57,151	487,574
Total	188,327	648,394
Unrealized Losses
Less Than 12 Months	(705)	(743)
12 Months or More	(591)	(12,067)
Total	(1,296)	(12,810)
State, county and municipal securities
Estimated Fair Value
Less Than 12 Months	803	23,784
12 Months or More	0	33,873
Total	803	57,657
Unrealized Losses
Less Than 12 Months	(2)	(52)
12 Months or More	0	(252)
Total	(2)	(304)
Corporate debt securities
Estimated Fair Value
Less Than 12 Months	2,573	17,291
12 Months or More	0	17,952
Total	2,573	35,243
Unrealized Losses
Less Than 12 Months	(2)	(111)
12 Months or More	0	(416)
Total	(2)	(527)
SBA pool securities
Estimated Fair Value
Less Than 12 Months	28,521	1,291
12 Months or More	4,825	61,966
Total	33,346	63,257
Unrealized Losses
Less Than 12 Months	(285)	(7)
12 Months or More	(124)	(1,782)
Total	(409)	(1,789)
Mortgage-backed securities
Estimated Fair Value
Less Than 12 Months	99,279	118,454
12 Months or More	52,326	373,783
Total	151,605	492,237
Unrealized Losses
Less Than 12 Months	(416)	(573)
12 Months or More	(467)	(9,617)
Total	$ (883)	$ (10,190)