Common Stock - Stock by Class (Details) - shares	Sep. 30, 2025	Dec. 31, 2024
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	29,955,166	27,147,526
Shares underlying outstanding stock options
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	4,987,566	4,631,750
Shares underlying unvested restricted stock units
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	7,558,342	7,020,251
Performance-based restricted stock units granted
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	1,268,235	1,290,684
Shares available for issuance under the 2018 Incentive Award Plan
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	9,659,638	8,079,498
Shares available for issuance under the 2018 Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	3,004,890	2,208,577
Shares available for issuance under the 2023 Employment Inducement Incentive Award Plan
Class of Stock [Line Items]
Common stock, shares reserved for future issuance (in shares)	3,476,495	3,916,766

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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+ Details

Guardant Health, Inc. 10-Q