Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Restricted cash deposit	$ 327,000	$ 327,000
Restricted cash noncurrent	327,000	327,000
Income tax expense (benefit)	0	0
Other income	515,000	$ 270,000	$ 1,001,000
Operating lease, right-of-use asset	4,988,000			$ 4,600,000
Operating lease liability	$ 6,150,000			$ 5,900,000
2018 Omnibus Incentive Plan [Member]
Significant Accounting Policies [Line Items]
Number of shares authorized for common stock for equity awards	5,001,000