Stock-based Compensation - Fair Value of Market Performance Units Estimated, Monte Carlo Simulation Model (Detail) - Performance Units [Member] - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
| Risk-free interest rate, Minimum | 0.65% | 0.25% | 0.13% |
| Risk-free interest rate, Maximum | 1.31% | 1.10% | 0.78% |
| Estimated volatility factor, Minimum | 34.00% | 39.00% | 40.00% |
| Estimated volatility factor, Maximum | 38.00% | 41.00% | |
| Expected dividends | $ 0 | $ 0 | |