Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (1,535)	$ 20
Reclassification adjustment		(20)	20
Other comprehensive income (loss)	(2,650)	(1,535)
Ending balance	(4,185)	(1,535)	20
Net Unrealized Gains (Reclassification Adjustment) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		20
Reclassification adjustment		(20)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(40)
Other comprehensive income (loss)	214	(40)
Ending balance	174	(40)
Defined Benefit Pension Obligation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,495)
Other comprehensive income (loss)	(2,864)	(1,495)
Ending balance	$ (4,359)	$ (1,495)