Subsequent Event - Summarized Estimate of Aggregate Carrying Amounts of the Major Classes of Assets and Liabilities Related to Disposed Business (Detail) - Skyfence Networks Ltd. [Member] $ in Thousands	Dec. 31, 2016 USD ($)
Assets
Accounts receivables	$ 463
Prepaid and other current assets	15
Property and equipment, net	234
Goodwill	1,179
Acquired intangible assets, net	4,668
Total assets	6,559
Liabilities:
Accounts payable	163
Accrued and other current liabilities	76
Deferred revenue	1,334
Total liabilities	$ 1,573