Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net (loss) earnings	$ (4,967)	$ 7,669	$ (9,622)	$ 24,486
Unrealized (loss) gain on short-term investments	(494)	12	523	(7)
Other unrealized gain				24
Changes in pension plan assets and benefit obligations	1	4	3	4
Tax effect of adjustments	178	(6)	(229)	3
Total comprehensive (loss) income	$ (5,282)	$ 7,679	$ (9,325)	$ 24,510