Summary of Contract Assets and Deferred Revenue (Detail) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Accounts Receivable Net [Line Items]
Contract assets	[1]	$ 2,888	$ 914
Long-term contract assets	[2]	1,581
Total contract assets		4,469	914
Deferred revenue	[3]	158,178	166,297
Long-term deferred revenue	[4]	5,840	3,706
Total deferred revenue		$ 164,018	$ 170,003

[1] Included in other current assets.

[2] Included in other long-term assets.

[3] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and has adjusted prior periods to conform. See Note 2. "New Accounting Pronouncements" for additional information.

[4] Included in other long-term liabilities.