Recently Issued Accounting Pronouncements - Summary of Impact of Adoption of Accounting Standards on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets:
Accounts receivable, net	$ 34,064		$ 34,461
Prepaid expenses and other current assets	6,455		5,714
Other assets	4,750		3,112
Liabilities:
Accrued expenses and other current liabilities	38,127		43,096
Deferred revenue			15,102
Deferred revenue	15,889		15,102
Other long-term liabilities	5,830		6,428
Deferred income taxes	27,135		28,004
Stockholders' equity:
Retained earnings	100,673		$ 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	5,729	7,052
Prepaid expenses and other current assets	108	427
Other assets	1,080	650
Liabilities:
Accrued expenses and other current liabilities	2,161
Deferred revenue		(2,923)
Deferred revenue	(1,660)
Other long-term liabilities	(468)	(825)
Deferred income taxes	184	2,927
Stockholders' equity:
Retained earnings	6,700	$ 8,950
Accounting Standards Update 2014-09 [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Assets:
Accounts receivable, net	28,335
Prepaid expenses and other current assets	6,347
Other assets	3,670
Liabilities:
Accrued expenses and other current liabilities	35,966
Deferred revenue	17,549
Other long-term liabilities	6,298
Deferred income taxes	26,951
Stockholders' equity:
Retained earnings	$ 93,973