INVESTMENT SECURITIES - Gross Unrealized Gains (Losses) and Fair Value by Length of Time (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investment securities
Fair value, less than twelve months	$ 25,435	$ 58,552
Gross unrealized losses, less than twelve months	(313)	(1,934)
Fair value, twelve months or greater	33,811	16,623
Gross unrealized losses, twelve months or greater	(1,125)	(988)
Fair value, total	59,246	75,175
Gross unrealized losses, total	(1,438)	(2,922)
Mortgage-backed securities
Investment securities
Fair value, less than twelve months	981	3,572
Gross unrealized losses, less than twelve months	(12)	(106)
Fair value, twelve months or greater	2,276	3,627
Gross unrealized losses, twelve months or greater	(99)	(58)
Fair value, total	3,257	7,199
Gross unrealized losses, total	(111)	(164)
State and political securities
Investment securities
Fair value, less than twelve months	15,691	26,113
Gross unrealized losses, less than twelve months	(104)	(509)
Fair value, twelve months or greater	3,018	0
Gross unrealized losses, twelve months or greater	(94)	0
Fair value, total	18,709	26,113
Gross unrealized losses, total	(198)	(509)
Other debt securities
Investment securities
Fair value, less than twelve months	7,512	28,140
Gross unrealized losses, less than twelve months	(148)	(1,179)
Fair value, twelve months or greater	28,517	12,240
Gross unrealized losses, twelve months or greater	(932)	(886)
Fair value, total	36,029	40,380
Gross unrealized losses, total	(1,080)	(2,065)
Total debt securities
Investment securities
Fair value, less than twelve months	24,184	57,825
Gross unrealized losses, less than twelve months	(264)	(1,794)
Fair value, twelve months or greater	33,811	15,867
Gross unrealized losses, twelve months or greater	(1,125)	(944)
Fair value, total	57,995	73,692
Gross unrealized losses, total	(1,389)	(2,738)
Other equity securities
Investment securities
Fair value, less than twelve months	1,251	727
Gross unrealized losses, less than twelve months	(49)	(140)
Fair value, twelve months or greater	0	756
Gross unrealized losses, twelve months or greater	0	(44)
Fair value, total	1,251	1,483
Gross unrealized losses, total	(49)	(184)
Total equity securities
Investment securities
Fair value, less than twelve months	1,251	727
Gross unrealized losses, less than twelve months	(49)	(140)
Fair value, twelve months or greater	0	756
Gross unrealized losses, twelve months or greater	0	(44)
Fair value, total	1,251	1,483
Gross unrealized losses, total	$ (49)	$ (184)