Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Lease liability	$ 954,000
Present value of remaining lease payments	1,016,000
Right-of-use asset	$ 954,000
ASC 842
Significant Accounting Policies [Line Items]
Lease liability		$ 1,362,000
Present value of remaining lease payments		$ 1,434,000
Incremental borrowing rate		4.00%
Right-of-use asset		$ 1,362,000