INVESTMENT OPERATIONS - Schedule of Realized Gain(Losses) on Equity Securities Sold (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Net gains (losses) recognized during the period on equity securities	$ (1,044)	$ (1,037)	$ (9,830)	$ (1,046)
Less: net gains (losses) recognized on equity securities sold during the period	(680)		(2,380)
Gains (losses) recognized during the period on equity securities still held	$ (364)		$ (7,449)