Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jan. 01, 2021 USD ($)	Dec. 31, 2021 USD ($) Segment $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Summary Of Significant Accounting Policies [Line Items]
Stock conversion ratio description		Upon the closing of the Merger, the common and convertible preferred units of Compass Therapeutics LLC were converted into the Company’s common stock. The Company effected a 0.15-for-one stock conversion ratio for its issued and outstanding convertible preferred units. Common units were converted using the same ratio after factoring in the relevant strike price of each grant.
Common units outstanding | shares		0
Convertible preferred units outstanding | shares		0
Preferred stock, shares authorized | shares		10,000,000	10,000,000
Preferred stock, par value | $ / shares		$ 0.0001	$ 0.0001
Common stock, shares authorized | shares		300,000,000	300,000,000
Common stock, par value | $ / shares		$ 0.0001	$ 0.0001
Number of operating segments | Segment		1
Restricted cash		$ 0	$ 200,000
Letter of credit			100,000
Impairment losses on long-lived assets		0	0
Expected dividend yield		0
Income tax expense		0	32,000
Operating lease, right-of-use ("ROU") asset		4,089,000	0
Operating lease liabilities		$ 4,037,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2021
Change in accounting principle, accounting standards update, transition option elected [Extensible List]	us-gaap:AccountingStandardsUpdate201602RetrospectiveMember
Operating lease, right-of-use ("ROU") asset	$ 5,100,000
Operating lease liabilities	$ 5,100,000
ASU 2019-12
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, immaterial effect		true
Common Stock
Summary Of Significant Accounting Policies [Line Items]
Purchase price per share | $ / shares		$ 5.00
Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents		$ 130,000,000.0	$ 43,600,000
Convertible Preferred Units
Summary Of Significant Accounting Policies [Line Items]
Stock conversion ratio		0.15