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Employee Benefit - Sensitivity Analysis of One-percentage Point Change in Assumed Rates (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Discount rate [Member]    
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]    
Assumption - 1% increase $ (984) $ (1,003)
Assumption - 1% decrease 1,159 1,178
Rate of salary increase [Member]    
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]    
Assumption - 1% increase 1,095 1,115
Assumption - 1% decrease $ (953) $ (973)