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Intangible Assets and Goodwill (Tables) | 3 Months Ended
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Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract] |
Intangible assets | Intangible assets, net of accumulated amortization, impairment charges and adjustments are summarized as follows:
|  |  | As of March 31, 2021 |  | As of December 31, 2020
(In millions) | Estimated Life |  | Cost |  | Accumulated Amortization |  | Net |  | Cost |  | Accumulated Amortization |  | Net
Completed technology | 4-28 years |  | $ | 7,394.3 |  |  | $ | (5,190.3) |  |  | $ | 2,204.0 |  |  | $ | 7,394.3 |  |  | $ | (5,136.5) |  |  | $ | 2,257.8 |
In-process research and development | Indefinite until commercialization |  | 720.1 |  |  | — |  |  | 720.1 |  |  | 762.5 |  |  | — |  |  | 762.5 |
Trademarks and trade names | Indefinite |  | 64.0 |  |  | — |  |  | 64.0 |  |  | 64.0 |  |  | — |  |  | 64.0 |
Total intangible assets |  |  | $ | 8,178.4 |  |  | $ | (5,190.3) |  |  | $ | 2,988.1 |  |  | $ | 8,220.8 |  |  | $ | (5,136.5) |  |  | $ | 3,084.3 |
Estimated future amortization for acquired intangible assets | The estimated future amortization of finite-lived intangible assets for the next five years is expected to be as follows:
(In millions) |  | As of March 31, 2021
2021 (remaining nine months) |  | $ | 165.0 |
2022 |  | 215.0 |
2023 |  | 215.0 |
2024 |  | 225.0 |
2025 |  | 220.0 |
2026 |  | 200.0 |
Summary of roll forward of the changes in goodwill | The following table provides a roll forward of the changes in our goodwill balance:
(In millions) |  | As of March 31, 2021
Goodwill, beginning of period |  | $ | 5,762.1 |
Other |  | 1.0 |
Goodwill, end of period |  | $ | 5,763.1 |

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