Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
GROSS OTHER COMPREHENSIVE (LOSS) INCOME
Amortization of actuarial loss on defined benefit pension plan	$ 7	$ 7	$ 117	$ 15
Unrealized gain (loss) on marketable securities, available-for-sale:
Unrealized gain (loss) on marketable securities, available -for-sale	(150)	360	(169)	596
Less: reclassification adjustments for gains (loss) included in net income	0	(124)	0	(172)
Total unrealized gain (loss) on marketable securities, available-for-sale	(150)	236	(169)	424
Other comprehensive income loss	(143)	243	(52)	439
TAX BENEFIT
Amortization of actuarial loss on defined benefit pension plan, tax	(3)	(3)	(45)	(6)
Unrealized gain (loss) on marketable securities, available-for-sale:
Unrealized gain (loss) on marketable securities, available -for-sale, tax	0	0	0	0
Less: reclassification adjustments for gains (loss) included in net income, tax	0	0	0	0
Total unrealized gain (loss) on marketable securities, available-for-sale, tax	0	0	0	0
Other comprehensive loss, tax	(3)	(3)	(45)	(6)
NET OTHER COMPREHENSIVE (LOSS) INCOME
Amortization of actuarial loss on defined benefit pension plan, net	4	4	72	9
Unrealized gain (loss) on marketable securities, available-for-sale:
Unrealized gain (loss) on marketable securities, available -for-sale, net	(150)	360	(169)	596
Less: reclassification adjustments for gains (loss) included in net income, net	0	(124)	0	(172)
Total unrealized gain (loss) on marketable securities, available-for-sale, net	(150)	236	(169)	424
Other comprehensive (loss) income, net	$ (146)	$ 240	$ (97)	$ 433