Accrued Severance Benefits - Additional Information (Detail) |
9 Months Ended |
|---|---|
Sep. 30, 2016 | |
| Percentage of employees eligible for severance benefits | 98.00% |
| Korea [Member] | Minimum [Member] | |
| Retirement age of employees | 57 years |
| Korea [Member] | Maximum [Member] | |
| Retirement age of employees | 60 years |