Reconciliation Between Effective Tax Rate and U.S. Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income before taxes on income	$ 18,899	$ 16,425	$ 7,381
Theoretical tax at U.S. statutory rate	6,426	5,585	2,510
Foreign income taxes at rates other than U.S. rate	(2,304)	(1,831)	(958)
Approved and benefited enterprises benefits	(2,698)	(2,767)	(1,653)
Subpart F	737	538	434
Non-deductible items	294	682	349
Non-taxable items	(529)	(505)	(481)
Changes in uncertain tax position	(1,757)	505
Stock-based compensation expense	(1,503)
Deemed mandatory repatriation	1,916
Changes in valuation allowance	2,076	1,212	839
Other, net	(787)	(94)	74
Taxes on income	$ 1,871	$ 3,325	$ 1,114