Debt - Additional Information (Details)			1 Months Ended			3 Months Ended
Debt - Additional Information (Details)	Oct. 01, 2021 USD ($) $ / shares	Nov. 22, 2019 USD ($) tranche $ / shares	Sep. 30, 2022 USD ($) $ / shares	Feb. 28, 2021 USD ($) shares	Aug. 31, 2020 USD ($) shares	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)
Loan Amendment
Debt Instrument [Line Items]
Financing costs						$ 313,000
K2 Health Ventures LLC \| Loan and Security Agreement
Debt Instrument [Line Items]
Commitment date stock price (in dollars per share) \| $ / shares		$ 2.33
Effective interest rate (as a percent)						15.99%
K2 Health Ventures LLC \| Term Loans \| Loan and Security Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 25,000,000
Number of potential tranches \| tranche		3
Final fee percentage (as a percent)		4.45%
Portion of outstanding term loan amount converted				$ 1,500,000	$ 2,000,000
Conversion price per share (USD per share) \| $ / shares		$ 1.56
Beneficial conversion feature		$ 2,101,000
Number of shares issued upon conversion of term loan (in shares) \| shares				961,538	1,282,050
Outstanding term loan principal balance						$ 14,000,000
Debt instrument interest rate, floating (as a percent)						13.25%
Interest expense						$ 932,000	$ 682,000
K2 Health Ventures LLC \| Term Loans \| Loan Amendment
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000,000
Final fee percentage (as a percent)	4.25%
Debt instrument interest rate, floating (as a percent)	8.50%
Interest rate percentage	3.25%
Debt instrument variable rate (as a percent)	5.25%
Amount of cash from financing activities needed to extend interest-only period	$ 100,000,000
Term of the combined facility (months)	48 months		48 months
Debt instrument, term, prepayment amount	$ 779,000
K2 Health Ventures LLC \| Term Loans \| Loan Amendment \| First $500 Converted at $1.56 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500,000		$ 500,000
Conversion price per share (USD per share) \| $ / shares	$ 1.56		$ 1.56
K2 Health Ventures LLC \| Term Loans \| Loan Amendment \| Additional Amounts Converted in Excess of $500 at $7.81 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500,000		$ 500,000
Conversion price per share (USD per share) \| $ / shares	$ 7.81		$ 1.83
K2 Health Ventures LLC \| Term Loans \| Maximum \| Loan and Security Agreement
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted		4,000,000
K2 Health Ventures LLC \| Term Loans \| Maximum \| Loan Amendment
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 4,500,000		$ 4,500,000
K2 Health Ventures LLC \| Term Loans \| Payment Occurs on or before Twenty Four Months after Initial Funding Date \| Loan Amendment
Debt Instrument [Line Items]
Prepayment penalty fee percentage (as a percent)	5.00%
Default interest rate (as a percent)	5.00%
K2 Health Ventures LLC \| Term Loans \| Prepayment Occurs More than Twenty Four Months after, but on or before Thirty Six Months after Initial Funding Date \| Loan Amendment
Debt Instrument [Line Items]
Prepayment penalty fee percentage (as a percent)	3.00%
K2 Health Ventures LLC \| Term Loans \| Prepayment Occurs More than Thirty Six Months after Initial Funding Date \| Loan Amendment
Debt Instrument [Line Items]
Prepayment penalty fee percentage (as a percent)	1.00%
K2 Health Ventures LLC \| First Tranche Term Loan \| Loan and Security Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		7,500,000
K2 Health Ventures LLC \| First Tranche Term Loan \| Loan Amendment
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000,000
K2 Health Ventures LLC \| Second Tranche Term Loan \| Loan and Security Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		10,000,000
K2 Health Ventures LLC \| Second Tranche Term Loan \| Loan Amendment
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	15,000,000
K2 Health Ventures LLC \| Third Tranche Term Loan \| Loan and Security Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 7,500,000
K2 Health Ventures LLC \| Third Tranche Term Loan \| Loan Amendment
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10,000,000

Surface Oncology, Inc. 10-Q