Share-Based Compensation - Weighted-Average Assumptions for Estimating Fair Values (Detail) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | ||
| Risk-free interest rate | 2.10% | 1.90% |
| Dividend yield | 1.60% | 1.70% |
| Expected life (years) | 5 years | 5 years |
| Expected volatility | 37.90% | 42.90% |