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Equity Incentive Plans - Narrative (Details) - USD ($) $ in Millions |  |  |  | 9 Months Ended
--- | --- | --- | --- | ---
Jan. 01, 2020 | Jan. 01, 2018 | Jan. 26, 2017 | Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Unrecognized compensation cost |  |  |  | $ 24.8
Weighted average period remaining for amortization of unrecognized compensation cost (in years) |  |  |  | 3 years 10 days
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
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 Equity Incentive 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) | 1,090,203 |  |  |
2017 Employee Stock Purchase Plan | Employee stock |  |  |  |
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) | 272,550 |  |  |

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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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 (a)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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