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Employee Stock and Benefit Plans (Tables)
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12 Months Ended |
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Dec. 31, 2013
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| Share-based Compensation [Abstract] |
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| Stock-based employee compensation |
Stock-based employee compensation is included in the consolidated statements of income as follows: | | | | | | | | | | | | | | | | Year Ended December 31, | | | 2013 | | 2012 | | 2011 | | | (in thousands) | Cost of revenues | | $ | 421 |
| | $ | 272 |
| | $ | 139 |
| Research and development | | 1,038 |
| | 649 |
| | 458 |
| Sales and marketing | | 1,244 |
| | 993 |
| | 579 |
| General and administrative | | 1,842 |
| | 1,008 |
| | 811 |
| Total stock-based employee compensation | | $ | 4,545 |
| | $ | 2,922 |
| | $ | 1,987 |
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| Fair value assumptions of options granted to employees |
The fair value of each option granted to employees is estimated on the date of grant using the Black-Scholes option-pricing model based on the following assumptions:
| | | | | | | | | | Year Ended December 31, | | | 2013 | | 2012 | | 2011 | Expected term (in years) | | 5.4 to 6.1 | | 5.3 to 6.1 | | 5.6 | Volatility | | 52% to 53% | | 52% to 53% | | 55% | Risk-free interest rate | | 0.7% to 1.5% | | 0.6% to 0.9% | | 0.9% to 2.3% | Dividend yield | | — | | — | | — |
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| Stock option activity |
A summary of the Company’s stock option activity is as follows: | | | | | | | | | | | | | | | | | Outstanding Shares | | Weighted Average Exercise Price | | Weighted Average Remaining Contractual Life (Years) | | Aggregate Intrinsic Value | | | | | | | | | (in thousands) | Balance as of December 31, 2010 | | 5,600,875 |
| | $ | 2.86 |
| | 6.4 | | $ | 6,964 |
| Granted | | 1,816,850 |
| | 5.06 |
| | | | | Exercised | | (432,687 | ) | | 3.09 |
| | | | | Canceled | | (672,997 | ) | | 3.89 |
| | | | | Balance as of December 31, 2011 | | 6,312,041 |
| | 3.36 |
| | 6.9 | | 16,012 |
| Granted | | 1,478,781 |
| | 8.94 |
| | | | | Exercised | | (724,316 | ) | | 2.86 |
| | | | | Canceled | | (552,998 | ) | | 6.79 |
| | | | | Balance as of December 31, 2012 | | 6,513,508 |
| | 4.39 |
| | 6.6 | | 67,711 |
| Granted | | 2,001,400 |
| | 15.78 |
| | | | | Exercised | | (952,871 | ) | | 4.32 |
| | | | | Canceled | | (522,944 | ) | | 10.71 |
| | | | | Balance as of December 31, 2013 | | 7,039,093 |
| | 7.17 |
| | 6.5 | | 112,312 |
| Vested and expected to vest—December 31, 2013 | | 6,472,113 |
| | 6.49 |
| | 6.3 | | 107,622 |
| Exercisable—December 31, 2013 | | 5,331,893 |
| | 4.32 |
| | 5.8 | | 85,073 |
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| Schedule of exercise price range, outstanding and vested |
The following table summarizes the outstanding and vested stock options at December 31, 2013: | | | | | | | | | | | | | | | | | | | | Outstanding | | Vested | Exercise Price | | Number of
Shares | | Weighted
Average
Exercise
Price Per
Share | | Weighted
Average
Remaining
Contractual
Life (Years) | | Number of
Shares | | Weighted
Average
Exercise
Price Per
Share | $0.10 - $1.90 | | 1,357,956 |
| | $ | 1.73 |
| | 2.9 | | 1,357,956 |
| | $ | 1.73 |
| $2.10 - $2.80 | | 582,998 |
| | 2.63 |
| | 4.7 | | 582,998 |
| | 2.63 |
| $3.80 - $3.80 | | 1,165,018 |
| | 3.80 |
| | 5.9 | | 879,766 |
| | 3.80 |
| $4.10 - $5.10 | | 1,116,084 |
| | 4.44 |
| | 6.9 | | 916,914 |
| | 4.37 |
| $5.90 - $10.77 | | 1,229,305 |
| | 8.64 |
| | 8.2 | | 399,243 |
| | 8.06 |
| $12.68 - $16.68 | | 1,003,657 |
| | 13.91 |
| | 9.0 | | 129,143 |
| | 13.24 |
| $20.80 - $23.81 |
| 584,075 |
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| 21.63 |
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| 9.7 |
| 10,537 |
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| 20.80 |
| | | 7,039,093 |
| | 7.17 |
| | 6.5 | | 4,276,557 |
| | 3.83 |
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