Significant Customers and Concentrations of Risk - Summary of Significant Customers from which the Company Derived 10% or More of Total Revenue (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Concentration Risk [Line Items]
Total revenues	$ 15,052,397	$ 13,478,763	$ 40,476,015	$ 38,025,925
Teva [Member]
Concentration Risk [Line Items]
Total revenues	7,663,701	5,522,996	17,043,954	18,513,972
AMAG [Member]
Concentration Risk [Line Items]
Total revenues	1,767,702	2,369,950	6,338,275	3,275,832
McKesson [Member]
Concentration Risk [Line Items]
Total revenues	2,339,238	1,946,261	6,333,080	5,501,810
AmerisourceBergen [Member]
Concentration Risk [Line Items]
Total revenues	1,470,268	1,156,566	4,323,013	3,658,453
Ferring [Member]
Concentration Risk [Line Items]
Total revenues	$ 723,502	$ 1,246,300	$ 3,018,098	$ 3,960,689