CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) [Abstract]
Net earnings (loss) available to common stockholders	$ 5,024	$ 9,710	$ 8,890	$ (68,211)
Other comprehensive income (loss):
Currency translation adjustment, net of taxes of $101 in the three months ended September 30, 2017, $(111) in the three months ended September 30, 2016, $285 in the nine months ended September 30, 2017 and $(456) in the nine months ended September 30, 2016	3,476	(156)	11,047	(3,199)
Unrealized gains (losses) on marketable securities arising during the period, net of taxes of $(21) in the three months ended September 30, 2017, $15 in the three months ended September 30, 2016, $(191) in the nine months ended September 30, 2017 and $74 in the nine months ended September 30, 2016	(33)	14	(300)	112
Change in unfunded SERP liability, net of taxes of $32 in the three months ended September 30, 2017, $32 in the three months ended September 30, 2016, $97 in the nine months ended September 30, 2017 and $136 in the nine months ended September 30, 2016	61	65	184	566
Other comprehensive income (loss)	3,504	(77)	10,931	(2,521)
Comprehensive income (loss)	$ 8,528	$ 9,633	$ 19,821	$ (70,732)