Restructuring Costs - Additional Information (Detail) $ in Thousands		1 Months Ended		3 Months Ended	8 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($) Employee	Oct. 31, 2019 Employee	May 31, 2019 Employee	Sep. 30, 2019 USD ($)	Dec. 31, 2019 Employee	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Restructuring Cost And Reserve [Line Items]
Expected aggregate restructuring charges	$ 472			$ 472		$ 472
Restructuring costs				253		1,629
Restructuring costs paid				442		782
Accrued restructuring charges	$ 472			472		472	$ 661
Severance Plan [Member]
Restructuring Cost And Reserve [Line Items]
Number of workforce elimination | Employee	34		38
Severance Plan [Member] | Scenario Forecast [Member]
Restructuring Cost And Reserve [Line Items]
Number of workforce expected to be eliminated | Employee					55
Severance Plan [Member] | Taiwan | Subsequent Event [Member]
Restructuring Cost And Reserve [Line Items]
Number of workforce expected to be eliminated | Employee		17
Severance and Benefits and Non-cash Impairment Charge [Member]
Restructuring Cost And Reserve [Line Items]
Expected aggregate restructuring charges	$ 2,100			2,100		2,100
Restructuring costs				300		1,600
Restructuring costs paid						800
Accrued restructuring charges	$ 500			$ 500		$ 500