Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Operating leases
Right-of-use assets from operating leases	$ 13,056	$ 13,300
Operating lease liabilities, current	$ 2,438
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesMember
Operating lease liabilities (Note 12)	$ 10,700
Total operating lease liabilities	13,138	$ 13,300
Finance leases
Finance leases right of use asset	$ 3,384
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentMember
Finance lease liabilities, current	$ 497
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesMember
Finance lease liabilities, non-current	$ 7,605
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesMember
Total finance lease liabilities	$ 8,102