Income Taxes - Reconciliation of Income Taxes Computed at Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Federal provision at statutory rate	$ 4,776	$ 2,392	$ 5,887
U.S./Foreign tax rate differential	(919)	(1,842)	1
Foreign non-deductible expenses	(2,006)	743	(479)
Foreign tax provision	615	336	296
State taxes, net of federal benefit	73	(171)	556
Change in uncertain tax positions	81	114	236
Change in valuation allowance	2,475	(1,858)	3,283
Tax credits	(152)	(104)	(283)
Share-based compensation	(657)	(108)	459
Repatriation of foreign earnings	3,964	0	0
Other	150	6	(230)
Provision for income taxes	15,350	49	9,758
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Change in tax rate	(264)	541	32
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Change in tax rate	$ 7,214	$ 0	$ 0