Significant Customers and Concentrations of Risk - Summary of Revenues by Customer Location (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Concentration Risk [Line Items]
Total revenues	$ 14,196,121	$ 13,478,763	$ 12,228,390	$ 12,318,772	$ 11,803,920	$ 11,085,752	$ 14,420,391	$ 8,348,037	$ 52,222,046	$ 45,658,100	$ 26,501,665
United States of America [Member]
Concentration Risk [Line Items]
Total revenues									45,531,470	39,228,615	21,409,371
Europe [Member]
Concentration Risk [Line Items]
Total revenues									6,116,865	6,025,899	4,761,684
Other [Member]
Concentration Risk [Line Items]
Total revenues									$ 573,711	$ 403,586	$ 330,610