Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (4,185)	$ (1,535)	$ 20
Reclassification adjustment			(20)
Other comprehensive income (loss)	8,020	(2,650)	(1,535)
Ending balance	3,835	(4,185)	(1,535)
Net Unrealized Gains (Reclassification Adjustment) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			20
Reclassification adjustment			(20)
Other comprehensive income (loss)	6,821
Ending balance	6,821
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	174	(40)
Other comprehensive income (loss)	393	214	(40)
Ending balance	567	174	(40)
Defined Benefit Pension Obligation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(4,359)	(1,495)
Other comprehensive income (loss)	806	(2,864)	(1,495)
Ending balance	$ (3,553)	$ (4,359)	$ (1,495)