Annual default interest rate percentage.

No definition available.

Name:	surf_AnnualDefaultInterestRatePercentage
Namespace Prefix:	surf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument commitment date stock price.

+ References

No definition available.

+ Details

Name:	surf_DebtInstrumentCommitmentDateStockPrice
Namespace Prefix:	surf_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt instrument final fee percentage.

+ References

No definition available.

+ Details

Name:	surf_DebtInstrumentFinalFeePercentage
Namespace Prefix:	surf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Term, Amount of Cash from Financing Activities Needed to Extend Interest-Only Period

+ References

No definition available.

+ Details

Name:	surf_DebtInstrumentTermAmountOfCashFromFinancingActivitiesNeededToExtendInterestOnlyPeriod
Namespace Prefix:	surf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Debt Instrument, Term, Prepayment Amount

+ References

No definition available.

+ Details

Name:	surf_DebtInstrumentTermPrepaymentAmount
Namespace Prefix:	surf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of potential tranches.

+ References

No definition available.

+ Details

Name:	surf_NumberOfPotentialTranches
Namespace Prefix:	surf_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Prepayment penalty fee percentage.

+ References

No definition available.

+ Details

Name:	surf_PrepaymentPenaltyFeePercentage
Namespace Prefix:	surf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionOriginalDebtAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of a favorable spread to a debt holder between the amount of debt being converted and the value of the securities received upon conversion. This is an embedded conversion feature of convertible debt issued that is in-the-money at the commitment date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21538-112644

+ Details

Name:	us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69F
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495745-112612

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69E
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495743-112612

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1F
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495355-112611

+ Details

Name:	us-gaap_InterestExpenseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585

+ Details

Name:	us-gaap_PaymentsOfDebtIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=surf_LoanAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=surf_K2HealthVenturesLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=surf_TermLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=surf_FirstTrancheTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=surf_SecondTrancheTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=surf_ThirdTrancheTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=surf_LoanAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=surf_First500000ConvertedAt156PerShareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=surf_AdditionalAmountsConvertedInExcessOf500000At781PerShareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=surf_PaymentOccursOnOrBeforeTwentyFourMonthsAfterInitialFundingDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=surf_PrepaymentOccursMoreThanTwentyFourMonthsAfterButOnOrBeforeThirtySixMonthsAfterInitialFundingDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=surf_PrepaymentOccursMoreThanThirtySixMonthsAfterInitialFundingDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	Oct. 01, 2021 USD ($) $ / shares	Nov. 22, 2019 USD ($) segment $ / shares	Aug. 31, 2020 USD ($) shares	Feb. 29, 2020 USD ($) shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)
Debt Instrument [Line Items]
Financing costs					$ 0	$ 0	$ 81
Loan and Security Agreement \| K2 Health Ventures LLC
Debt Instrument [Line Items]
Commitment date stock price (in dollars per share) \| $ / shares		$ 2.33
Loan and Security Agreement \| K2 Health Ventures LLC \| Term Loans
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 25,000
Number of potential tranches \| segment		3
Final fee percentage		4.45%
Portion of outstanding term loan amount converted			$ 2,000	$ 1,500
Conversion price per share (in dollars per share) \| $ / shares		$ 1.56
Beneficial conversion feature		$ 2,101
Number of shares issued upon conversion of term loan (shares) \| shares			1,282,050	961,538
Outstanding term loan principal balance				$ 14,000
Interest expense					2,546	$ 2,745	$ 147
Loan and Security Agreement \| K2 Health Ventures LLC \| Term Loans \| Maximum
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted		4,000
Loan and Security Agreement \| K2 Health Ventures LLC \| First Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		7,500
Loan and Security Agreement \| K2 Health Ventures LLC \| Second Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		10,000						$ 10,000
Loan and Security Agreement \| K2 Health Ventures LLC \| Third Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 7,500
Loan Amendment
Debt Instrument [Line Items]
Financing costs					$ 313
Loan Amendment \| K2 Health Ventures LLC \| Term Loans
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000
Final fee percentage	4.25%
Debt instrument interest rate, floating	8.50%
Interest rate, stated percentage	3.25%
Debt instrument variable rate	5.25%
Term of the combined facility (months)	48 months
Aggregate amount needed to extend period	$ 100,000
Prepayment amount	779
Loan Amendment \| K2 Health Ventures LLC \| Term Loans \| First $500,000 Converted at $1.56 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500
Conversion price per share (in dollars per share) \| $ / shares	$ 1.56
Loan Amendment \| K2 Health Ventures LLC \| Term Loans \| Additional Amounts Converted in Excess of $500,000 at $7.81 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500
Conversion price per share (in dollars per share) \| $ / shares	$ 7.81
Loan Amendment \| K2 Health Ventures LLC \| Term Loans \| Maximum
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 4,500
Loan Amendment \| K2 Health Ventures LLC \| Term Loans \| Payment Occurs on or before Twenty Four Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	5.00%
Default interest rate	5.00%
Loan Amendment \| 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
Debt Instrument [Line Items]
Prepayment penalty fee percentage	3.00%
Loan Amendment \| K2 Health Ventures LLC \| Term Loans \| Prepayment Occurs More than Thirty Six Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	1.00%
Loan Amendment \| K2 Health Ventures LLC \| First Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000
Loan Amendment \| K2 Health Ventures LLC \| Second Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	15,000
Loan Amendment \| K2 Health Ventures LLC \| Third Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10,000