CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) earnings	$ (5,321)	$ 8,838
Unrealized gain on short-term investments	14	32
Changes in pension plan assets and benefit obligations	(1)	(7)
Tax effect	(5)	(10)
Total comprehensive income	$ (5,313)	$ 8,853