Fair Value Measurements of Pension Plan Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,042	$ 910	$ 835
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,042	910
TAIWAN
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	827	729
TAIWAN | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	827	729
GERMANY
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	215	181
GERMANY | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 215	$ 181