Leases - Schedule of Classification of ROU Assets and Lease liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Operating right-of-use assets	$ 1,304
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Finance right-of-use assets	$ 189
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Total leased assets	$ 1,493
Current
Short-term obligations under operating leases	$ 876	$ 0
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Short-term obligations under finance leases	$ 80	91
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Noncurrent
Operating leases	$ 562	0
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LiabilitiesNoncurrent
Finance leases	$ 117	$ 132
Total lease liabilities	$ 1,635