Stock-based Compensation Expense (Tables)
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12 Months Ended |
Dec. 31, 2019 |
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| Share-based Payment Arrangement [Abstract] |
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| Stock-based compensation expense by line item |
The effect of stock-based compensation expense during the three years ended December 31, 2019 was as follows: | | | | | | | | | | | | | | 2019 | | 2018 | | 2017 | | (in thousands) | Stock-based compensation expense by line item: | | | | | | Cost of sales | $ | 5,575 |
| | $ | 4,543 |
| | $ | 2,500 |
| Research and development expenses | 224,558 |
| | 203,112 |
| | 181,900 |
| Sales, general and administrative expenses | 130,356 |
| | 117,392 |
| | 108,836 |
| Total stock-based compensation expense included in costs and expenses | 360,489 |
| | 325,047 |
| | 293,236 |
| Income tax effect | (124,225 | ) | | — |
| | — |
| Total stock-based compensation included in costs and expenses, net of tax | $ | 236,264 |
| | $ | 325,047 |
| | $ | 293,236 |
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| Stock-based compensation expense by type of award |
The stock-based compensation expense by type of award during the three years ended December 31, 2019 was as follows: | | | | | | | | | | | | | | 2019 | | 2018 | | 2017 | | (in thousands) | Stock-based compensation expense by type of award: | | | | | | Restricted stock and restricted stock units (including PSUs) | $ | 254,276 |
| | $ | 207,845 |
| | $ | 181,258 |
| Stock options | 96,737 |
| | 107,854 |
| | 105,367 |
| ESPP share issuances | 11,196 |
| | 9,933 |
| | 9,017 |
| Stock-based compensation expense related to inventories | (1,720 | ) | | (585 | ) | | (2,406 | ) | Total stock-based compensation expense included in costs and expenses | $ | 360,489 |
| | $ | 325,047 |
| | $ | 293,236 |
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| Unrecognized stock-based compensation expense, net of estimated forfeitures |
The following table sets forth the Company’s unrecognized stock-based compensation expense as of December 31, 2019, by type of award and the weighted-average period over which that expense is expected to be recognized: | | | | | | | | As of December 31, 2019 | | Unrecognized Expense | | Weighted-average Recognition Period | | (in thousands) | | (in years) | Type of award: | | | | Restricted stock and restricted stock units (including PSUs) | $ | 374,185 |
| | 2.05 | Stock options | $ | 130,153 |
| | 2.50 | ESPP share issuances | $ | 4,724 |
| | 0.55 |
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| Schedule of assumptions used to estimate the grant date fair value of options |
The fair value of each option granted during 2019, 2018 and 2017 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions: | | | | | | | | | | | 2019 | | 2018 | | 2017 | Expected stock price volatility | 36.99 | % | | 40.50 | % | | 45.31 | % | Risk-free interest rate | 2.32 | % | | 2.61 | % | | 1.94 | % | Expected term of options (in years) | 4.27 |
| | 4.55 |
| | 4.68 |
| Expected annual dividends | — |
| | — |
| | — |
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| Schedule of assumptions used to estimate the grant date fair value employee stock purchase plan |
The following table reflects the weighted-average assumptions used in the Black-Scholes option pricing model for 2019, 2018 and 2017: | | | | | | | | | | | 2019 | | 2018 | | 2017 | Expected stock price volatility | 33.43 | % | | 36.51 | % | | 39.09 | % | Risk-free interest rate | 2.08 | % | | 2.36 | % | | 1.24 | % | Expected term (in years) | 0.74 |
| | 0.75 |
| | 0.75 |
| Expected annual dividends | — |
| | — |
| | — |
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