Net Income (Loss) Per Share - Summary of Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net loss	$ (5,597)	$ (13,784)	$ (30,894)	$ (44,796)
Weighted average shares outstanding	42,038	28,688	42,013	27,784
Diluted shares outstanding (in shares)	42,038	28,688	42,013	27,784
Basic - net loss per share (in dollars per share)	$ (0.13)	$ (0.48)	$ (0.74)	$ (1.61)
Diluted - net loss per share (in dollars per share)	(0.13)	(0.48)	(0.74)	(1.61)
Cash dividends declared per share (in dollars per share)	$ 0.07	$ 0.07	$ 0.21	$ 0.21