ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		$ 598,567	$ 565,868	$ 493,947
Other comprehensive income (loss) before reclassifications		(1,338)	1,429
Amounts reclassified from accumulated other comprehensive income (loss)		(1,400)	1,582
Other comprehensive income (loss), net of tax		(2,738)	3,011	2,862
Reclassification of tax effects on other comprehensive income	[1]	32	(713)
Balance		$ 602,081	$ 598,567	565,868
Corporate income tax rate		21.00%	35.00%
ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		$ 598,567
Reclassification of unrealized gains and losses on available-for-sale equity securities			$ 0
Balance			598,567
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(3,641)	(5,939)	(8,801)
Balance		(6,500)	(3,641)	(5,939)
Accumulated Other Comprehensive Loss [Member] | ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(3,794)
Reclassification of unrealized gains and losses on available-for-sale equity securities	[2]		(153)
Balance			(3,794)
Securities Held-to-Maturity and Transferred Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		0	(713)
Other comprehensive income (loss) before reclassifications		0	39
Amounts reclassified from accumulated other comprehensive income (loss)		0	674
Other comprehensive income (loss), net of tax		0	713
Reclassification of tax effects on other comprehensive income	[1]	0	0
Balance		0	0	(713)
Securities Held-to-Maturity and Transferred Securities [Member] | ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		0
Reclassification of unrealized gains and losses on available-for-sale equity securities	[2]		0
Balance			0
Securities Available-for-Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		285	(92)
Other comprehensive income (loss) before reclassifications		(1,159)	307
Amounts reclassified from accumulated other comprehensive income (loss)		(930)	20
Other comprehensive income (loss), net of tax		(2,089)	327
Reclassification of tax effects on other comprehensive income	[1]	0	50
Balance		(1,957)	285	(92)
Securities Available-for-Sale [Member] | ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		132
Reclassification of unrealized gains and losses on available-for-sale equity securities	[2]		(153)
Balance			132
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(6,633)	(6,910)
Other comprehensive income (loss) before reclassifications		311	786
Amounts reclassified from accumulated other comprehensive income (loss)		0	733
Other comprehensive income (loss), net of tax		311	1,519
Reclassification of tax effects on other comprehensive income	[1]	32	(1,242)
Balance		(6,290)	(6,633)	(6,910)
Defined Benefit Plans [Member] | ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(6,633)
Reclassification of unrealized gains and losses on available-for-sale equity securities	[2]		0
Balance			(6,633)
Derivative Asset [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		2,707	1,776
Other comprehensive income (loss) before reclassifications		(490)	297
Amounts reclassified from accumulated other comprehensive income (loss)		(470)	155
Other comprehensive income (loss), net of tax		(960)	452
Reclassification of tax effects on other comprehensive income	[1]	0	479
Balance		1,747	2,707	$ 1,776
Derivative Asset [Member] | ASU 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		$ 2,707
Reclassification of unrealized gains and losses on available-for-sale equity securities	[2]		0
Balance			$ 2,707

[1] Represents the impact of adopting ASU 2018-02 allowing the reclassification of certain stranded income tax effects in accumulated other comprehensive income resulting from the Tax Cuts and Jobs Act of 2017 from accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act of 2017 (the "Tax Act") (or portion thereof) is recorded. The amount of the reclassification is the difference between the historical corporate income tax rate (35%) and the newly enacted 21% corporate income tax rate. The reclassification is as of and for the year ended December 31, 2017; no prior period information has been retroactively adjusted as a result of implementing the ASU.

[2] Represents the impact of adopting ASU 2016-01 allowing the reclassification of unrealized gains and losses on available-for-sale equity securities from accumulated other comprehensive income to Retained Earnings.