Net Loss per Share - Computation of Denominators Used in Net Loss per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic:
Weighted average common shares outstanding	39,818,162	33,315,809	39,685,954	33,000,487
Diluted:
Weighted average common shares outstanding - Basic	39,818,162	33,315,809	39,685,954	33,000,487
Common stock options	0	0	0	0
Denominator for diluted net loss per share	39,818,162	33,315,809	39,685,954	33,000,487