MARKETABLE SECURITIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($) security	Dec. 31, 2016 USD ($)
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment losses on debt securities related to credit losses | $	$ 0	$ 0
Securities in unrealized loss positions, over 12 months	95
Securities in unrealized loss positions, less than 12 months	75
Available-for-sale, securities in unrealized loss positions, over 12 months	37
Held-to-maturity, securities in unrealized loss positions, over 12 months	58
Available-for-sale securities in unrealized loss positions, less than 12 months	13
Held-to-maturity, securities in unrealized loss positions, less than 12 months	62
Fair value of securities pledged as collateral | $	$ 259,557,000	$ 245,600,000
Number of held-to-maturity securities sold	0	3
Amortized cost | $		$ 3,140,000	$ 1,842,000
Other Than Temporary Impairment
Debt Securities, Available-for-sale [Line Items]
Amortized cost | $		324,000
Principal Write-downs
Debt Securities, Available-for-sale [Line Items]
Amortized cost | $		$ 499,000
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Number of held-to-maturity securities sold		3
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Number of held-to-maturity securities sold		2