Revenue Recognition - Summary of Impact of Adoption of New Revenue Standard on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 22,393	$ 31,699
Deferred Cost, current	5,038	2,429
Deferred Cost (non-current)	7,478
Liabilities and Stockholders’ Equity
Other current liabilities	1,331	808
Deferred revenue	71,000	73,072
Accumulated deficit	(112,497)	(109,252)
Accounting Standards Update 2014-09 | Adjustments Due to ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	78	100
Deferred Cost, current		2,132
Deferred Cost (non-current)		6,965
Liabilities and Stockholders’ Equity
Other current liabilities	78	100
Accumulated deficit	9,081	9,097
Accounting Standards Update 2014-09 | Balances Without Adoption of ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	22,315	31,799
Deferred Cost, current		4,551
Deferred Cost (non-current)		6,965
Liabilities and Stockholders’ Equity
Other current liabilities	1,253	908
Deferred revenue	71,000	73,072
Accumulated deficit	$ (121,578)	$ (100,155)