Stock-Based Compensation - Additional information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions |
9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Outstanding Ending balance | 14,439 | 14,713 | 19,656 | 18,542 | |
| Weighted average grant date fair value (in dollars per share) | $ 12.85 | $ 2.40 | $ 2.67 | $ 1.41 | $ 0.51 |
| Intrinsic value | $ 50.5 | $ 0.5 | $ 3.6 | $ 0.3 | $ 0.0 |
| Performance and Market Based Options | |||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Granted | 0 | 600 | |||
| Outstanding Ending balance | 3,433 | 3,433 | |||
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Details
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