Recently Adopted Accounting Standard - Summary of Cumulative Effect of Adoption on Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Jun. 30, 2017
Item Effected [Line Items]
Accounts receivable, net	$ 45,056
Inventories, net	41,753		$ 36,499
Total assets	190,843		165,724	$ 163,615
Income taxes payable	526		300
Deferred revenue	4,610		5,791
Sales allowances	550
Total liabilities	31,905		29,305
Retained earnings	109,078		93,605
Total equity	158,938		136,419
Total liabilities and equity	190,843		$ 165,724
Accounting Standards Update 2014-09 [Member]
Item Effected [Line Items]
Sales allowances	550
Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Item Effected [Line Items]
Accounts receivable, net	(39)
Inventories, net	(97)
Total assets	(136)
Income taxes payable	(18)
Deferred revenue	4,445
Sales allowances	(466)
Total liabilities	3,961
Retained earnings	(4,097)	$ 3,670
Total equity	(4,097)
Total liabilities and equity	(136)
Accounting Standards Update 2014-09 [Member] | Balances without adoption of Topic 606 [Member]
Item Effected [Line Items]
Accounts receivable, net	45,017
Inventories, net	41,656
Total assets	190,707
Income taxes payable	508
Deferred revenue	9,055
Sales allowances	84
Total liabilities	35,866
Retained earnings	104,981
Total equity	154,841
Total liabilities and equity	$ 190,707