Revenue Recognition - Summary of Impact of Adoption of New Revenue Standard on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 33,064		$ 31,699
Deferred Cost			2,429
Other current liabilities	791		808
Deferred revenue (short and long term)	82,463		73,072
Accumulated deficit	(129,415)		$ (109,252)
Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net		$ 31,799
Deferred Cost		4,551
Deferred Cost (non-current)		6,965
Other current liabilities		908
Deferred revenue (short and long term)		73,072
Accumulated deficit		(100,155)
Accounting Standards Update 2014-09 | Adjustments Due to ASC 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	209	100
Deferred Cost		2,132
Deferred Cost (non-current)		6,965
Other current liabilities	209	100
Accumulated deficit	8,888	$ 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	32,855
Other current liabilities	582
Deferred revenue (short and long term)	82,463
Accumulated deficit	$ (138,303)