Stock-Based Compensation and Employee Benefit Plans - Narrative (Details) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 01, 2024 shares	Oct. 31, 2020 USD ($) shares	Jun. 30, 2025 USD ($) shares	Jun. 30, 2024 USD ($) shares	Jun. 30, 2025 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value (in dollars per share) \| $ / shares					$ 0.96	$ 7.36
Unrecognized compensation cost			$ 10,200		$ 10,200
Intrinsic value of options exercised					0	$ 1,900
Aggregate intrinsic value of options exercisable			100		100
Aggregate intrinsic value of options outstanding			100		100
Total stock-based compensation			1,890	$ 2,665	$ 3,611	5,140
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period					1 year 3 months 18 days
Expected dividends					0.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period					1 year 2 months 12 days
Total stock-based compensation					$ 700	$ 1,100
Unrecognized compensation cost for RSU			$ 3,500		$ 3,500
2020 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares authorized, percentage of capital stock outstanding							0.04
Common stock, additional capital shares reserved for future issuance (in shares) \| shares	1,908,588
Shares reserved for future issuance (in shares) \| shares			3,873,241		3,873,241
Stock-based compensation, vesting period					4 years
Share-based compensation, expiration period					10 years
2020 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares authorized, percentage of capital stock outstanding		0.01
Common stock, additional capital shares reserved for future issuance (in shares) \| shares	1,653,370
Purchase price of common stock in percent		85.00%
Contribution limit in percentage of employee's eligible compensation		15.00%
Maximum value of shares per employee during any calendar year		$ 25
Maximum number of shares per employee during any one purchase period (in shares) \| shares		600
Annual increase in number of shares authorized, term					10 years
Stock issued under ESPP (in shares) \| shares			0	0	6,859	7,286
Proceeds from ESPP					$ 100	$ 100

Shattuck Labs, Inc. 10-Q