Accrued Severance Benefits - Changes in Accrued Severance Benefits (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Dec. 31, 2015 |
|
| Postemployment Benefits [Abstract] | |||||
| Beginning balance | $ 132,800 | $ 144,800 | $ 135,160 | $ 140,405 | |
| Provisions | 3,782 | 2,296 | 13,609 | 14,173 | |
| Severance payments | (1,076) | (3,674) | (14,178) | (7,905) | |
| Translation adjustments | 8,350 | (8,466) | 9,265 | (11,717) | |
| Ending balance | 143,856 | 134,956 | 143,856 | 134,956 | |
| Less: Cumulative contributions to the National Pension Fund | (305) | (310) | (305) | (310) | |
| Group severance insurance plan | (705) | (691) | (705) | (691) | |
| Accrued severance benefits, net | $ 142,846 | $ 133,955 | $ 142,846 | $ 133,955 | $ 134,148 |