Consolidated Balance Sheets (Parenthetical) - $ / shares |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Statement Of Financial Position [Abstract] | ||
| Preferred stock, par value | $ 0.01 | $ 0.01 |
| Preferred stock, shares authorized | 500,000 | 500,000 |
| Preferred stock, shares issued | 0 | 0 |
| Preferred stock, shares outstanding | 0 | 0 |
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 125,000,000 | 125,000,000 |
| Common stock, shares issued | 21,719,000 | 21,063,000 |
| Common stock, shares outstanding | 18,361,000 | 17,752,000 |
| Treasury stock, shares | 3,358,000 | 3,311,000 |