Stock-Based Compensation - Schedule of Restricted Stock Units, Activity (Details) - Restricted Stock Units (RSUs) - $ / shares shares in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Shares | |||
| Outstanding at beginning of year (in shares) | 285 | 350 | 423 |
| Granted (in shares) | 144 | 181 | 104 |
| Vested (in shares) | (171) | (206) | (171) |
| Forfeited or canceled (in shares) | (37) | (40) | (6) |
| Outstanding at end of year (in shares) | 221 | 285 | 350 |
| Weighted Average Exercise Price Per Share | |||
| Outstanding at beginning of year (in dollars per share) | $ 23.01 | $ 22.47 | $ 19.28 |
| Granted (in dollars per share) | 23.74 | 21.25 | 26.69 |
| Vested (in dollars per share) | 23.18 | 20.56 | 19.03 |
| Forfeited or canceled (in dollars per share) | 21.69 | 22.68 | 19.86 |
| Outstanding at end of year (in dollars per share) | $ 23.58 | $ 23.01 | $ 22.47 |