Fair Value Measurements of Pension Plan Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 910	$ 835	$ 908
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	910	835
TAIWAN, PROVINCE OF CHINA
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	729	669
TAIWAN, PROVINCE OF CHINA | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	729	669
GERMANY
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	181	166
GERMANY | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 181	$ 166