COMPONENTS OF THE COMPANY'S CONDENSED CONSOLIDATED BALANCE SHEETS Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (2,514)		$ (1,652)		$ (2,710)		$ (1,851)
Other comprehensive income (loss) before reclassifications	46		85		193		244
Amounts reclassified from accumulated other comprehensive income (loss)	49		40		98		80
Net-current period other comprehensive income (loss)	95		125		291		324
Ending balance	(2,419)		(1,527)		(2,419)		(1,527)
Unrealized Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(137)		116		(220)		(97)
Other comprehensive income (loss) before reclassifications	15		48		98		261
Amounts reclassified from accumulated other comprehensive income (loss)	0		0		0		0
Net-current period other comprehensive income (loss)	15		48		98		261
Ending balance	(122)		164		(122)		164
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,887)		(1,544)		(1,936)		(1,584)
Other comprehensive income (loss) before reclassifications	0		0		0		0
Amounts reclassified from accumulated other comprehensive income (loss)	49	[1]	40	[1]	98	[2]	80	[2]
Net-current period other comprehensive income (loss)	49		40		98		80
Ending balance	(1,838)		(1,504)		(1,838)		(1,504)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(490)		(224)		(554)		(170)
Other comprehensive income (loss) before reclassifications	31		37		95		(17)
Amounts reclassified from accumulated other comprehensive income (loss)	0		0		0		0
Net-current period other comprehensive income (loss)	31		37		95		(17)
Ending balance	$ (459)		$ (187)		$ (459)		$ (187)

[1] This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the three months ended June 30, 2017 and 2016.

[2] This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost for the six months ended June 30, 2017 and 2016.