Net Loss per Share - Computation of Denominators Used in Net Loss per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic:
Weighted average common shares outstanding	44,517,134	38,034,216	41,314,044	34,696,835
Diluted:
Weighted average common shares outstanding - Basic	44,517,134	38,034,216	41,314,044	34,696,835
Common stock options	0	0	0	0
Denominator for diluted net loss per share	44,517,134	38,034,216	41,314,044	34,696,835