Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating Leases
Operating lease right-of-use assets	$ 1,559	$ 0
Total operating lease liabilities	2,388
Finance Leases
Property and equipment, net	2,675	$ 2,993
Total finance lease liabilities	$ 50
Weighted Average Remaining Lease Term
Operating leases	4 years
Finance leases	2 years
Weighted Average Discount Rate
Operating leases	6.00%
Finance leases	16.20%
Finance Lease [Member]
Finance Leases
Property and equipment, at cost	$ 66
Accumulated depreciation	(13)
Property and equipment, net	53
Other Noncurrent Liabilities [Member]
Finance Leases
Total finance lease liabilities	22
Other Current Liabilities [Member]
Operating Leases
Total operating lease liabilities	642
Finance Leases
Total finance lease liabilities	28
Operating Lease Liabilities [Member]
Operating Leases
Total operating lease liabilities	$ 1,746