Schedule of Changes in Accumulated Balances of Other Comprehensive Income (Loss), Net of Taxes (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Revenues:
Licensing and related revenue	$ 10,083	$ 9,535
Royalties	7,486	11,752
Total revenues	17,569	21,287
Cost of revenues	1,972	1,696
Gross profit	15,597	19,591
Operating expenses:
Sales and marketing	3,176	2,938
Total operating expenses	18,505	15,245
Operating income	(2,908)	4,346
Financial income, net	927	571
Income (loss) before taxes on income	(1,981)	4,917
Income taxes	201	810
Net income (loss)	$ (2,182)	$ 4,107
Basic net income per share	$ (0.10)	$ 0.19
Diluted net income per share	$ (0.10)	$ 0.19
Assets:
Trade receivables	$ 13,902		$ 14,480
Accrued revenues	9,425		2,014
Prepaid expenses and other current assets	4,136		3,747
Liabilities:
Deferred revenues	4,973		4,399
Stockholders' equity:
Retained earnings	60,204		$ 53,873
Accumulated Other Comprehensive Income (Loss)
Revenues:
Licensing and related revenue	10,083
Royalties	7,486
Total revenues	17,569
Cost of revenues	1,972
Gross profit	15,597
Operating expenses:
Sales and marketing	3,176
Other operating expenses	15,329
Total operating expenses	18,505
Operating income	(2,908)
Financial income, net	927
Income (loss) before taxes on income	(1,981)
Income taxes	201
Net income (loss)	$ (2,182)
Basic net income per share	$ (0.10)
Diluted net income per share	$ (0.10)
Assets:
Trade receivables	$ 13,902
Accrued revenues	9,425
Prepaid expenses and other current assets	4,136
Liabilities:
Deferred revenues	4,973
Stockholders' equity:
Retained earnings	60,204
Accumulated Other Comprehensive Income (Loss) | Calculated under Revenue Guidance in Effect before Topic 606 [Member] | ASU 2014-09
Revenues:
Licensing and related revenue	9,564
Royalties	9,968
Total revenues	19,532
Cost of revenues	1,972
Gross profit	17,560
Operating expenses:
Sales and marketing	3,166
Other operating expenses	15,329
Total operating expenses	18,495
Operating income	(935)
Financial income, net	927
Income (loss) before taxes on income	(8)
Income taxes	464
Net income (loss)	$ (472)
Basic net income per share	$ (0.02)
Diluted net income per share	$ (0.02)
Assets:
Trade receivables	$ 13,856
Accrued revenues	2,314
Prepaid expenses and other current assets	4,531
Liabilities:
Deferred revenues	5,056
Stockholders' equity:
Retained earnings	53,359
Accumulated Other Comprehensive Income (Loss) | Effect of change higher/(lower) | ASU 2014-09
Revenues:
Licensing and related revenue	519
Royalties	(2,482)
Total revenues	(1,963)
Gross profit	(1,963)
Operating expenses:
Sales and marketing	10
Total operating expenses	10
Operating income	(1,973)
Income (loss) before taxes on income	(1,973)
Income taxes	(263)
Net income (loss)	$ (1,710)
Basic net income per share	$ (0.08)
Diluted net income per share	$ (0.08)
Assets:
Trade receivables	$ 46
Accrued revenues	7,111
Prepaid expenses and other current assets	(395)
Liabilities:
Deferred revenues	(83)
Stockholders' equity:
Retained earnings	$ 6,845