INVESTMENT IN EQUITY SECURITIES (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Number of investment shares acquired (in shares)					4.1
Purchase of investment securities					$ 48,200
Investment in equity securities	$ 43,185		$ 43,185			$ 49,153
Unrealized gain (loss) on investment in equity securities	1,533	$ 0	(5,968)	$ 0
Unrealized gain (loss) on investment in equity securities, net of income taxes (OCI)	0	(6,981)	0	5,742
Investment income, dividend	$ 600	$ 600	$ 1,200	$ 1,200