Accumulated Other Comprehensive (Loss) Income - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 3,835
Other comprehensive (loss) income	(3,963)
Ending balance	(128)
Unrealized Gains on Marketable Securities, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	6,821
Other comprehensive (loss) income	(3,986)
Ending balance	2,835
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	567
Other comprehensive (loss) income	(32)
Ending balance	535
Defined Benefit Pension Obligation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,553)
Other comprehensive (loss) income	55
Ending balance	$ (3,498)