Accrued Severance Benefits - Changes in Accrued Severance Benefits (Detail) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Jun. 30, 2016 |
Dec. 31, 2016 |
|
| Postemployment Benefits [Abstract] | |||||
| Beginning balance | $ 140,878 | $ 139,103 | $ 130,144 | $ 135,160 | |
| Provisions | 3,390 | 4,056 | 10,776 | 9,827 | |
| Severance payments | (10,558) | (9,004) | (18,082) | (13,102) | |
| Translation adjustments | (2,816) | (1,355) | 8,056 | 915 | |
| Ending balance | 130,894 | 132,800 | 130,894 | 132,800 | |
| Less: Cumulative contributions to the National Pension Fund | (245) | (290) | (245) | (290) | |
| Group severance insurance plan | (599) | (669) | (599) | (669) | |
| Accrued severance benefits, net | $ 130,050 | $ 131,841 | $ 130,050 | $ 131,841 | $ 129,225 |