OTHER INCOME: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
OTHER INCOME, NET:
Interest and dividend income	$ 1,421	$ 1,582	$ 1,445
Gains on trading securities relating to deferred compensation plans	1,450	4,901	10,588
Interest expense	(76)	(99)	(92)
Pretax gain on step acquisition		1,821
Impairment of equity investment			(975)
Equity method investment loss			(967)
Foreign exchange gains (losses)	(1,427)	(861)	(790)
Capital gains (losses)	2	(219)	2,576
Miscellaneous, net	126	246	345
Total other income, net	$ 1,496	$ 7,371	$ 12,130