Summary of Significant Accounting Policies and Select Balance Sheet Information - Balance Sheet Classification and Amounts of Right-of-Use Assets and Lease Liabilities (Detail) $ in Thousands	Sep. 30, 2020 USD ($)
Right-of-use assets:
Other assets	$ 2,508
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Operating lease liabilities:
Other accrued liabilities	$ 436
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherAccruedLiabilitiesCurrent
Other long-term liabilities	$ 3,340
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Total operating lease liabilities	$ 3,776