Summary of Company's RSU Activity (Detail) - Restricted Stock Units $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Number of Shares
Granted | shares	383,811
Cancelled/forfeited | shares	(10,105)
Outstanding, Ending Balance | shares	373,706
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Granted | $ / shares	$ 21.07
Weighted Average Grant Date Fair Value, Cancelled/forfeited | $ / shares	21.28
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 21.07
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding | $	$ 6,042,826