Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities (Detail) - USD ($) $ in Thousands |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Zero Cost Collars [Member] | ||
| Asset Derivatives: | ||
| Derivatives designated as hedging instruments, Asset | $ 2 | |
| Liabilities Derivatives: | ||
| Derivatives designated as hedging instruments, Liability | 888 | $ 453 |
| Forward [Member] | ||
| Liabilities Derivatives: | ||
| Derivatives designated as hedging instruments, Liability | 73 | |
| Other Current Assets [Member] | Zero Cost Collars [Member] | ||
| Asset Derivatives: | ||
| Derivatives designated as hedging instruments, Asset | 2 | |
| Other Current Liabilities [Member] | Zero Cost Collars [Member] | ||
| Liabilities Derivatives: | ||
| Derivatives designated as hedging instruments, Liability | 888 | $ 453 |
| Other Current Liabilities [Member] | Forward [Member] | ||
| Liabilities Derivatives: | ||
| Derivatives designated as hedging instruments, Liability | $ 73 |