Provision Benefit for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Foreign	$ 274	$ 255	$ 225
Federal	0	0	0
State	0	2	0
Total current	274	257	225
Foreign	0	0	0
Federal	6	4	3
State	4	2	1
Total deferred	10	6	4
Provision for income taxes	$ 284	$ 263	$ 229