Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Statement Of Financial Position [Abstract] | ||
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 500,000,000 | 500,000,000 |
| Common stock, shares issued | 181,720,136 | 180,907,483 |
| Treasury Stock, shares | 3,721,496 | 2,625,112 |