EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator [Abstract]
Net earnings (loss)	$ 3,120	$ 22,776	$ 3,866	$ (77,921)
Undistributed earnings (loss)	2,300	21,967	2,217	(79,542)
Class A [Member]
Numerator [Abstract]
Net earnings (loss)	530	3,987	646	(13,718)
Less dividends declared	131	131	261	261
Undistributed earnings (loss)	$ 399	$ 3,856	$ 385	$ (13,979)
Weighted-average shares outstanding [Abstract]
Basic and diluted (in shares)	2,175	2,175	2,175	2,175
Net earnings (loss) per share [Abstract]
Basic and diluted (in dollars per share)	$ 0.24	$ 1.83	$ 0.30	$ (6.31)
Class B [Member]
Numerator [Abstract]
Net earnings (loss)	$ 2,590	$ 18,789	$ 3,220	$ (64,203)
Less dividends declared	689	678	1,388	1,360
Undistributed earnings (loss)	$ 1,901	$ 18,111	$ 1,832	$ (65,563)
Weighted-average shares outstanding [Abstract]
Basic and diluted (in shares)	9,859	9,729	9,852	9,715
Net earnings (loss) per share [Abstract]
Basic and diluted (in dollars per share)	$ 0.26	$ 1.93	$ 0.33	$ (6.61)