Income Taxes - Summary of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Deferred tax assets:
NOLs - Foreign	$ 5,747	$ 3,841
Stock-based compensation	2,206	1,474
Deferred rent liability	1,195	1,257
NOLs - U.S.	762	909
Accrued expenses	1,611	526
Other	207	488
Deferred tax assets	11,728	8,495
Deferred tax liabilities:
Unrealized gains	1,666	1,718
Fixed assets	1,495	1,498
Goodwill and intangible assets	522	388
Prepaid assets	85
Deferred tax liabilities	3,768	3,604
Total deferred tax assets less deferred tax liabilities	7,960	4,891
Less: valuation allowance	(5,747)	(3,841)
Deferred tax assets, net	$ 2,213	$ 1,050