Recent Accounting Pronouncements - Summary of Impact of Adoption of Accounting Standards on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets:
Accounts receivable, net	$ 36,491		$ 34,461
Prepaid expenses and other current assets	7,491		5,714
Other assets	6,313		3,112
Liabilities:
Accrued expenses and other current liabilities	31,127		43,096
Deferred revenue			15,102
Deferred revenue	13,771		15,102
Other long-term liabilities	6,925		6,428
Deferred income taxes	26,351		28,004
Stockholders' equity:
Retained earnings	96,477		$ 97,815
Accounting Standards Update 2014-09 [Member]
Assets:
Accounts receivable, net		$ 41,513
Prepaid expenses and other current assets		6,141
Other assets		3,762
Liabilities:
Deferred revenue		12,179
Other long-term liabilities		5,603
Deferred income taxes		30,931
Stockholders' equity:
Retained earnings		106,765
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Assets:
Accounts receivable, net	7,583	7,052
Prepaid expenses and other current assets	190	427
Other assets	2,934	650
Liabilities:
Accrued expenses and other current liabilities	2,161
Deferred revenue		(2,923)
Deferred revenue	(2,684)
Other long-term liabilities	(468)	(825)
Deferred income taxes	1,304	2,927
Stockholders' equity:
Retained earnings	10,394	$ 8,950
Accounting Standards Update 2014-09 [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Assets:
Accounts receivable, net	28,908
Prepaid expenses and other current assets	7,301
Other assets	3,379
Liabilities:
Accrued expenses and other current liabilities	28,966
Deferred revenue	16,455
Other long-term liabilities	7,393
Deferred income taxes	25,047
Stockholders' equity:
Retained earnings	$ 86,083