Taxes on Income Comprised (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic taxes, current	$ (227)	$ 6	$ 115
Domestic taxes, deferred	0	0	0
Foreign taxes, current	3,473	3,932	2,212
Foreign taxes, deferred	(1,375)	(613)	(1,213)
Taxes on income	1,871	3,325	1,114
Income (loss) before taxes on income, domestic	(5,946)	(3,488)	(3,360)
Income (loss) before taxes on income, foreign	24,845	19,913	10,741
Income before taxes on income	$ 18,899	$ 16,425	$ 7,381