Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Operating Leases
Operating lease right-of-use assets	$ 1,477	$ 0
Total operating lease liabilities	2,261
Finance Leases
Property and equipment, net	2,263	$ 2,993
Total finance lease liabilities	$ 45
Weighted Average Remaining Lease Term
Operating leases	4 years
Finance leases	2 years
Weighted Average Discount Rate
Operating leases	6.00%
Finance leases	13.80%
Finance Lease [Member]
Finance Leases
Property and equipment, at cost	$ 66
Accumulated depreciation	(17)
Property and equipment, net	49
Other Noncurrent Liabilities [Member]
Finance Leases
Total finance lease liabilities	23
Other Current Liabilities [Member]
Operating Leases
Total operating lease liabilities	646
Finance Leases
Total finance lease liabilities	22
Operating Lease Liabilities [Member]
Operating Leases
Total operating lease liabilities	$ 1,605