| Schedule of quarterly financial information |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended | | Dec 31, 2013 | | Sept 30, 2013 | | June 30, 2013 | | March 31, 2013 | | Dec 31, 2012 | | Sept 30, 2012 | | June 30, 2012 | | March 31, 2012 | | (in thousands, except per share amounts) | Total revenues | $ | 81,459 |
| | $ | 61,079 |
| | $ | 49,884 |
| | $ | 40,018 |
| | $ | 41,806 |
| | $ | 32,126 |
| | $ | 29,116 |
| | $ | 24,685 |
| Gross profit | 75,409 |
| | 56,501 |
| | 45,538 |
| | 36,468 |
| | 38,423 |
| | 29,317 |
| | 26,617 |
| | 23,014 |
| Net income (loss) | 11,245 |
| | 2,441 |
| | (2,575 | ) | | (4,035 | ) | | (1,056 | ) | | 367 |
| | 1,059 |
| | 1,057 |
| Net income (loss) per share attributable to common stockholders: | | | | | | | | | | | | | | | | Basic | $ | 0.18 |
| | $ | 0.04 |
| | $ | (0.05 | ) | | $ | (0.12 | ) | | $ | (0.03 | ) | | $ | 0.00 |
| | $ | 0.01 |
| | $ | 0.01 |
| Diluted | $ | 0.16 |
| | $ | 0.03 |
| | $ | (0.05 | ) | | $ | (0.12 | ) | | $ | (0.03 | ) | | $ | 0.00 |
| | $ | 0.01 |
| | $ | 0.01 |
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