Provision Benefit for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Foreign	$ 255	$ 225	$ 181
Federal	0	0	0
State	2	0	0
Total current	257	225	181
Foreign	0	0	0
Federal	4	3	3,659
State	2	1	47
Total deferred	6	4	3,706
Provision for income taxes	$ 263	$ 229	$ 3,887