|
Share-based compensation 3 (Details) (USD $)
|
6 Months Ended |
|
Jun. 30, 2012
|
| Share-Based Compensation [Abstract] |
|
| Number of Shares Outstanding Options Start |
2,323,091 |
| Number of Shares Granted |
343,158 |
| Issuance of common stock pursuant to the exercise of stock options, Shares |
(13,500) |
| Number of Shares Canceled or forfeited |
(20,822) |
| Number of Shares Outstanding Options Ending |
2,631,927 |
| Number of Shares Options exercisable |
1,665,787 |
| Weighted Average Grant Date Fair Value outstanding options Start |
$ 4.79 |
| Weighted Average Grant Date Fair Value Granted |
$ 2.56 |
| Weighted Average Grant Date Fair Value Excercised |
$ 1.35 |
| Weighted Average Grant Date Fair Value Canceled or Forfeited |
$ 4.47 |
| Weighted Average Grant Date Fair Value outstanding options End |
$ 4.52 |
| Weighted Average Grant Date Fair Value Options Exercisable |
$ 4.78 |
| Weighted Average Excercise Price Outstanding Options Start |
$ 12.93 |
| Weighted Average Excercise Price Granted |
$ 6.18 |
| Weighted Average Excercise Price Excercised |
$ 2.22 |
| Weighted Average Excercise Price Canceled or forfeited |
$ 11.19 |
| Weighted Average Excercise Price Outstanding Options End |
$ 12.12 |
| Weighted Average Excercise Price Options Excerciseable |
$ 13.62 |
| Weighted Average Remaining Contractual Life (in years) Outstanding options Start |
4.30 |
| Weighted Average Remaining Contractual Life (in years) Options exercisable |
3.22 |
| Weighted Average Remaining Contractual Life (in years) Outstanding options End |
4.18 |