CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| CONSOLIDATED BALANCE SHEETS | ||
| Ordinary shares, par value (in dollars per share) | $ 0.0001 | $ 0.0001 |
| Ordinary shares, shares authorized | 500,000,000 | 500,000,000 |
| Ordinary shares, shares issued | 237,926,352 | 237,853,602 |
| Ordinary shares, shares outstanding | 237,926,352 | 237,853,602 |