FAIR VALUE MEASUREMENTS - RECURRING (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Marketable Securities	$ 114,682
Recurring
Marketable Securities	114,682	$ 75,897
Available-for-sale Securities
Marketable Securities	114,182	75,397
Corporate
Marketable Securities	19,307	24,391
Corporate | Recurring
Marketable Securities	19,307	24,391
Corporate | Level 2 | Recurring
Marketable Securities	19,307	24,391
US Agencies
Marketable Securities	15,102	16,846
US Agencies | Recurring
Marketable Securities	15,102	16,846
US Agencies | Level 2 | Recurring
Marketable Securities	15,102	16,846
US Agencies - MBS
Marketable Securities	34,093	12,716
US Agencies - MBS | Recurring
Marketable Securities	34,093	12,716
US Agencies - MBS | Level 2 | Recurring
Marketable Securities	34,093	12,716
Obligations of states and political subdivisions
Marketable Securities	45,680	21,444
Obligations of states and political subdivisions | Recurring
Marketable Securities	45,680	21,444
Obligations of states and political subdivisions | Level 2 | Recurring
Marketable Securities	44,692	20,444
Obligations of states and political subdivisions | Level 3 | Recurring
Marketable Securities	988	1,000
Equity securities
Marketable Securities	500
Equity securities | Recurring
Marketable Securities	500	500
Equity securities | Level 3 | Recurring
Marketable Securities	$ 500	$ 500