Disposition of Business - Schedule of Carrying Amounts Immediately Preceding Disposition (Detail) - Skyfence Networks Ltd. [Member] $ in Thousands	Feb. 23, 2017 USD ($)
Assets
Prepaid and other current assets	$ 46
Property and equipment, net	219
Goodwill	1,058
Acquired intangible assets, net	4,496
Total assets	5,819
Liabilities
Accounts payable	104
Accrued and other current liabilities	117
Deferred revenue	1,454
Total liabilities	$ 1,675