Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income Taxes [Line Items]
Liability for uncertain tax positions	$ 100		$ 100		$ 300
Deferred income taxes on undistributed earnings			13	$ (595)
Income tax expense (benefit)	$ 206	$ 739	$ 1,549	$ (2,569)
Effective income tax rate	(468.20%)	27.70%	19.40%	(38.10%)
Zhongli [Member]
Income Taxes [Line Items]
Income tax expense (benefit)		$ (4,400)		$ (4,400)
Foreign Subsidiaries [Member]
Income Taxes [Line Items]
Deferred income taxes on undistributed earnings			$ (500)		$ (700)