Commitments and Contingencies - Lease Expense (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Balance as of December 31, 2019	$ 1,003,000
Amortization	(44,000)
Balance as of March 31, 2020	959,000
Lease expense	$ 67,000	$ 66,000