SECURITIES - Held to Maturity Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Held to maturity:
Less than 12 months, Estimated Fair Value	$ 8,286	$ 49,527
Less than 12 months, Gross Unrealized losses	(26)	(404)
Greater than 12 months, Estimated Fair Value	116,491	60,518
Greater than 12 months, Gross Unrealized losses	(3,802)	(1,870)
State and municipal obligations
Held to maturity:
Less than 12 months, Estimated Fair Value	8,286	7,709
Less than 12 months, Gross Unrealized losses	(26)	(57)
Greater than 12 months, Estimated Fair Value	22,142	1,009
Greater than 12 months, Gross Unrealized losses	(250)	(7)
U.S. GSE residential mortgage-backed securities
Held to maturity:
Less than 12 months, Estimated Fair Value	0	1,359
Less than 12 months, Gross Unrealized losses	0	(16)
Greater than 12 months, Estimated Fair Value	9,352	9,804
Greater than 12 months, Gross Unrealized losses	(336)	(245)
U.S. GSE residential collateralized mortgage obligations
Held to maturity:
Less than 12 months, Estimated Fair Value	0	21,329
Less than 12 months, Gross Unrealized losses	0	(94)
Greater than 12 months, Estimated Fair Value	40,665	21,112
Greater than 12 months, Gross Unrealized losses	(1,130)	(572)
U.S. GSE commercial mortgage-backed securities
Held to maturity:
Less than 12 months, Estimated Fair Value	0	8,789
Less than 12 months, Gross Unrealized losses	0	(121)
Greater than 12 months, Estimated Fair Value	16,205	8,303
Greater than 12 months, Gross Unrealized losses	(620)	(317)
U.S. GSE commercial collateralized mortgage obligations
Held to maturity:
Less than 12 months, Estimated Fair Value	0	10,341
Less than 12 months, Gross Unrealized losses	0	(116)
Greater than 12 months, Estimated Fair Value	28,127	20,290
Greater than 12 months, Gross Unrealized losses	$ (1,466)	$ (729)