Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares |
Jun. 30, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Statement Of Financial Position [Abstract] | ||
| Preferred stock, par value | $ 0.001 | $ 0.001 |
| Preferred stock, shares authorized | 15,000,000 | 15,000,000 |
| Preferred stock, shares issued | 0 | 0 |
| Preferred stock, shares outstanding | 0 | 0 |
| Common stock, par value | $ 0.001 | $ 0.001 |
| Common stock, shares authorized | 150,000,000 | 150,000,000 |
| Common stock, shares issued | 52,066,000 | 52,006,000 |
| Common stock, shares outstanding | 45,534,000 | 45,474,000 |
| Treasury stock, shares | 6,532,000 | 6,532,000 |