Incentive Share-Based Plan and Other Employee Benefits - Summary of Share-Based Option Transaction (Details) - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Options Granted for Common Shares | |||
| Outstanding at beginning of period | 962,255 | 940,683 | 1,031,058 |
| Granted | 86,831 | 190,448 | 64,514 |
| Exercised | (285,568) | (152,508) | (146,089) |
| Forfeited | (802) | (16,368) | (8,800) |
| Outstanding at end of period | 762,716 | 962,255 | 940,683 |
| Exercisable at end of period | 481,959 | 617,014 | |
| Weighted Average Exercise Price | |||
| Outstanding at beginning of period | $ 7.42 | $ 5.92 | $ 5.52 |
| Granted | 15.66 | 12.90 | 10.71 |
| Exercised | 5.62 | 5.31 | 5.18 |
| Forfeited | 16.96 | 4.85 | 5.91 |
| Outstanding at end of period | 7.42 | 7.42 | $ 5.92 |
| Exercisable at end of period | $ 7.29 | $ 5.72 | |
| Weighted Average Remaining Contractual Term | |||
| Outstanding at end of period | 4 years 6 months | ||
| Exercisable at end of period | 3 years 9 months 29 days | 4 years 1 month 17 days | |
| Aggregate Intrinsic Value | |||
| Outstanding at end of period | $ 14,348 | ||
| Exercisable at end of period | $ 9,426 | $ 7,091 | |