Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 900,000	$ 900,000	$ 900,000
Subsequent impairment of the underlying assets	0
Expected annual amortization expense for 2020	200,000
Expected annual amortization expense for 2021	200,000
Expected annual amortization expense for 2022	200,000
Expected annual amortization expense for 2023	200,000
Expected annual amortization expense for 2024	200,000
Expected annual amortization expense for 2025	200,000
Expected annual amortization expense for 2026	$ 200,000