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Equity Incentive Plans - Narrative (Details) - USD ($) $ in Millions |  |  | 6 Months Ended
--- | --- | --- | ---
Jan. 01, 2021 | Jan. 01, 2018 | Jun. 30, 2021
ESPP |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Weighted average period remaining for amortization of unrecognized compensation cost (in years) |  |  | 4 months 17 days
Unrecognized compensation cost |  |  | $ 0.2
Options to purchase common stock |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Award vesting period (in years) |  |  | 4 years
Award expiration period (in years) |  |  | 10 years
Unrecognized compensation cost |  |  | $ 36.8
Weighted average period remaining for amortization of unrecognized compensation cost (in years) |  |  | 2 years 8 months 15 days
Options to purchase common stock | Director Stock options |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Award vesting period (in years) |  |  | 1 year
Award expiration period (in years) |  |  | 10 years
2017 Plan |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Annual increase in number of shares available for issuance |  | 4.00% |
Capital shares reserved for future issuance, increase (in shares) | 1,094,223 |  |
ESPP | ESPP |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Annual increase in number of shares available for issuance |  | 1.00% |
Capital shares reserved for future issuance, increase (in shares) | 273,555 |  |

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- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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