CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ (1,500)	$ 7,047	$ 22,251	$ (3,410)
OTHER COMPREHENSIVE INCOME, NET OF TAX:
Unrealized gain (loss) on available-for-sale securities, net of tax of $92, $2, $139 and $(6), respectively	(171)	(5)	(256)	(9)
Employee benefit plan:
Actuarial gain (loss), net of tax of $(5), none, $195, and none, respectively	(5)		(358)
Amortization of prior service cost and actuarial loss for retirement plan included in net periodic pension costs, net of tax of $141, $157, $443 and $401, respectively	278	279	814	713
Net change for employee benefit plan	273	279	456	713
Change in cumulative foreign currency translation adjustment	12		32
TOTAL OTHER COMPREHENSIVE INCOME	114	274	232	704
COMPREHENSIVE INCOME (LOSS)	$ (1,386)	$ 7,321	$ 22,483	$ (2,706)