Leases - Schedule of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Abstract]
Operating cash flows from operating leases	$ 87	$ 82
Weighted-average remaining lease term, operating leases	3 years 3 months 18 days	4 years 3 months 18 days
Weighted-average discount rate, operating leases	11.80%	11.80%