Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Domestic NOLs	$ 6,320,893	$ 6,761,452
Foreign NOLs	8,323,454	4,094,141
Accrued expenses	19,597	793,148
Amortization	1,187,512	254,990
Deferred revenue	49,373	78,565
Stock compensation	589,986	561,749
Deferred rent	110,731	11,954
Depreciation	6,955	(6,081)
Total deferred tax assets	16,608,501	12,549,918
Deferred tax liabilities:
IPR&D assets	(8,856,561)	(2,607,364)
Prepaid expenses		(54,549)
IRC §481(a) adjustment	(20,118)	(32,194)
Total deferred tax liabilities	(8,876,679)	(2,694,107)
Deferred tax assets, net	7,731,822	9,855,811
Valuation allowance	(13,670,224)	$ (9,855,811)
Total deferred tax liabilities, net	$ (5,938,402)