NET EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator [Abstract]
Net earnings (loss)	$ 9,710	$ 4,920	$ (68,211)	$ 16,302
Less dividends declared: [Abstract]
Undistributed earnings (loss)	8,896	4,109	(70,647)	13,870
Undistributed earnings (loss) allocation - basic and diluted [Abstract]
Total undistributed earnings (loss)	8,896	4,109	(70,647)	13,870
Net earnings (loss) allocation - basic and diluted [Abstract]
Net earnings (loss)	9,710	4,920	(68,211)	16,302
Class A Common Shares [Member]
Numerator [Abstract]
Net earnings (loss)	1,688	852	(12,008)	2,833
Less dividends declared: [Abstract]
Dividends declared	131	130	392	391
Undistributed earnings (loss) allocation - basic and diluted [Abstract]
Total undistributed earnings (loss)	1,557	722	(12,400)	2,442
Net earnings (loss) allocation - basic and diluted [Abstract]
Net earnings (loss)	$ 1,688	$ 852	$ (12,008)	$ 2,833
Weighted-average shares outstanding [Abstract]
Common share - basic and diluted (in shares)	2,175	2,175	2,175	2,175
Net earnings (loss) per share [Abstract]
Common share - basic and diluted (in dollars per share)	$ 0.78	$ 0.39	$ (5.52)	$ 1.30
Class B Common Shares [Member]
Numerator [Abstract]
Net earnings (loss)	$ 8,022	$ 4,068	$ (56,203)	$ 13,469
Less dividends declared: [Abstract]
Dividends declared	683	681	2,044	2,041
Undistributed earnings (loss) allocation - basic and diluted [Abstract]
Total undistributed earnings (loss)	7,339	3,387	(58,247)	11,428
Net earnings (loss) allocation - basic and diluted [Abstract]
Net earnings (loss)	$ 8,022	$ 4,068	$ (56,203)	$ 13,469
Weighted-average shares outstanding [Abstract]
Common share - basic and diluted (in shares)	9,760	9,719	9,730	9,694
Net earnings (loss) per share [Abstract]
Common share - basic and diluted (in dollars per share)	$ 0.82	$ 0.42	$ (5.78)	$ 1.39