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Stockholders' Equity (Equity Incentive Plans) (Narrative) (Details) - shares | 1 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2018 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2016 | Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Shares authorized |  |  |  |  |  | 400,000
Additional shares authorized | 600,000 |  |  |  |  |
Shares available for grant | 1,000,000 |  |  |  |  |
Predetermined offering period, lower fair market value percentage |  |  | 85.00% |  |  |
Number of shares purchased under ESPP |  |  | 114,321 | 140,856 |  |
Shares available for future sale |  |  | 744,823 |  |  |
Stock Options [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Shares authorized |  | 5,000,000 |  |  | 2,000,000 |
Expiration period |  |  |  |  | 10 years |
Additional shares authorized | 3,000,000 | 3,000,000 |  |  |  |
Shares available for grant | 8,000,000 | 5,000,000 |  |  |  |
Shares available for future sale |  |  | 3,447,642 |  |  |

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- Definition Aggregate number of common shares reserved for future issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + 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 -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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