Equity and Equity Compensation Plans - Summary of Common Stock Reserved for Future Issuance: 2017 ESPP (Details) - 2017 Employee Stock Purchase Plan - shares	Sep. 30, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance at beginning of period (in shares)	4,039,667	3,330,271
Shares issued during the period (in shares)	(135,426)	(320,609)
Total shares reserved for future issuance (in shares)	3,904,241	3,009,662

Aggregate number of common shares reserved for future issuance.

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)
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- Definition

The shares that, although not legally released, will be released by a future scheduled and committed debt service payment and will be allocated to employees for service rendered in the current accounting period. The ESOP documents typically define the period of service to which the shares relate. ESOP shares are released to compensate employees directly, to settle employer liabilities for other employee benefits, and to replace dividends on allocated shares that are used for debt service.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109244661&loc=d3e17540-113929

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- Definition

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

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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.

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No definition available.

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