Consolidated Balance Sheets (Parenthetical) - $ / shares |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Statement of Financial Position [Abstract] | ||
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 150,000,000 | 150,000,000 |
| Common stock, shares issued | 42,384,836 | 41,627,103 |
| Common stock, shares outstanding | 34,010,627 | 35,048,338 |
| Treasury stock, shares | 8,374,209 | 6,578,765 |