The PPP/HCEA Act authorized additional funding under the CARES Act amount.

No definition available.

Name:	bksc_AdditionalFundingOfLoansToBeIssuedUnderCaresAct
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of funding provided to customers as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	bksc_BankFunding
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of customers that received funding as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	bksc_BankFundingNumberOfCustomers
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of loan processing fees recognized during the period.

+ References

No definition available.

+ Details

Name:	bksc_FeeIncomeLoans
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of financing receivables that are 90 days or more past due and still accruing.

+ References

No definition available.

+ Details

Name:	bksc_FinancingReceivableNumberInvestments90DaysPastDueAndStillAccruing
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percent guaranteed by the SBA of PPP loans.

+ References

No definition available.

+ Details

Name:	bksc_GuaranteeOfLoanBySbaPercent
Namespace Prefix:	bksc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of loan applications approved.

+ References

No definition available.

+ Details

Name:	bksc_LoanApplicationsApproved
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of loan applications received.

+ References

No definition available.

+ Details

Name:	bksc_LoanApplicationsReceived
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate loan balance of loans that received principal deferments during the period.

+ References

No definition available.

+ Details

Name:	bksc_LoanBalanceOfPrincipalDeferredLoans
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate loan balance of principal deferred loans not classified as troubled debt restructurings that were paid in full during the period.

+ References

No definition available.

+ Details

Name:	bksc_LoanBalanceOfPrincipalDeferredLoansNotClassifiedAsTroubledDebtRestructuringsPaidInFull
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate loan balance of principal deferred loans not classified as troubled debt restructurings that were past due during the period.

+ References

No definition available.

+ Details

Name:	bksc_LoanBalanceOfPrincipalDeferredLoansNotClassifiedAsTroubledDebtRestructuringsPastDue
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate loan balance of principal deferred loans not classified as troubled debt restructurings that were paying as agreed during the period.

+ References

No definition available.

+ Details

Name:	bksc_LoanBalanceOfPrincipalDeferredLoansNotClassifiedAsTroubledDebtRestructuringsPayingAsAgreed
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The Coronavirus Aid, Relief, and Economic Security Act was signed into law, which established the Paycheck Protection Program and the allocated amount of loans to be issued by financial institutions.

+ References

No definition available.

+ Details

Name:	bksc_LoansToBeIssuedUnderCaresAct
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of loan applications approved.

+ References

No definition available.

+ Details

Name:	bksc_NumberOfLoanApplicationsApproved
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of loan applications received.

+ References

No definition available.

+ Details

Name:	bksc_NumberOfLoanApplicationsReceived
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of principal deferments processed during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDeferments
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of customers that received principal deferments not classified as troubled debt restructurings during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsNotClassifiedAsTroubledDebtRestructurings
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of customers that received principal deferments not classified as troubled debt restructurings that paid in full during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsNotClassifiedAsTroubledDebtRestructuringsPaidInFull
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of customers that received principal deferments not classified as troubled debt restructurings that were past due during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsNotClassifiedAsTroubledDebtRestructuringsPastDue
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of customers that received principal deferments not classified as troubled debt restructurings that were paying as agreed during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsNotClassifiedAsTroubledDebtRestructuringsPayingAsAgreed
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of customers that received principal deferments during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsNumberOfCustomers
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of the loan portfolio that received principal deferments during the period.

+ References

No definition available.

+ Details

Name:	bksc_PrincipalDefermentsPercentageOfPortfolio
Namespace Prefix:	bksc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of processing fee for Paycheck Protection Program loans.

+ References

No definition available.

+ Details

Name:	bksc_ProcessingFee
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage processing fee received by the Bank based on the size of the loan from the SBA.

+ References

No definition available.

+ Details

Name:	bksc_ProcessingFeeOfSbaLoansPercent
Namespace Prefix:	bksc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of restructured debt payable based on the occurrence of future events or circumstances.

+ References

No definition available.

+ Details

Name:	bksc_RestructuredLoans
Namespace Prefix:	bksc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of restructured loans as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	bksc_RestructuredLoansNumber
Namespace Prefix:	bksc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ 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 (a)
-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 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

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

+ References

+ Details

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

- 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

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the aggregate value of loans, trade receivables, securities and financial instruments that serve as collateral for obligations arising from a transfer of financial assets recorded as a secured borrowing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5086-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCollateralForSecuredBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=123392090&loc=d3e45377-112738

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5074-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10152-111534

+ Details

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

- Definition

Cash received for fees during the current period. This element excludes cash proceeds from license fees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bksc_PaycheckProtectionProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=bksc_LoansRangeTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=bksc_LoansRangeThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=bksc_LoansRangeFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=bksc_SecondRoundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
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_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=bksc_LoansRangeOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOANS AND ALLOWANCE FOR LOAN LOSSES (Details Narrative)			3 Months Ended	12 Months Ended
LOANS AND ALLOWANCE FOR LOAN LOSSES (Details Narrative)	Dec. 27, 2020 USD ($)	Mar. 27, 2020 USD ($)	Mar. 31, 2021 USD ($) Number	Dec. 31, 2020 USD ($) Number	Apr. 24, 2020 USD ($)
Deferred loan fees			$ 830,945	$ 676,155
Loans pledged as collateral to secure funding with the Federal Reserve Bank			$ 91,000,000	$ 76,000,000
Number of loans over 90 days past due and still accruing \| Number			0	0
Restructured loans number \| Number			12	14
Restructured loans amount			$ 5,300,000	$ 5,800,000
Principal deferments amount				$ 700,000
Principal deferments number of customers \| Number				84
Loan balance of principal deferred loans				$ 25,900,000
Principal deferments percentage of portfolio				0.24%
Principal deferments number classified as TDRs \| Number			6	8
Loan balance of principal deferred loans classified as TDRs			$ 3,500,000	$ 3,900,000
Principal deferments number not classified as TDRs \| Number			75
Principal deferments number not classified as TDRs paid in full \| Number			22
Loan balance of principal deferred loans not classified as TDRs paid in full			$ 5,100,000
Principal deferments number not classified as TDRs past due \| Number			7
Loan balance of principal deferred loans not classified as TDRs past due			$ 800,000
Principal deferments number not classified as TDRs paying as agreed \| Number			46
Loan balance of principal deferred loans not classified as TDRs paying as agreed			$ 21,600,000
Paycheck Protection Program [Member]
Loans to be issued under CARES Act		$ 349,000,000,000
Loans fixed rate	1.00%	1.00%
Term of loan	5 years	2 years
Guarantee of loan by SBA (percent)	100.00%	100.00%
Processing fees received			1,400,000
Processing fees recognized				$ 600,000
Additional funding of loans to be issued under CARES Act	$ 325,000,000,000				$ 310,000,000,000
Bank funding amount			$ 37,800,000
Bank funding number of customers \| Number			266
Paycheck Protection Program [Member] \| Loans Range Two [Member]
Processing fee of SBA loans (percent)	5.00%
Paycheck Protection Program [Member] \| Loans Range Three [Member]
Processing fee of SBA loans (percent)	3.00%
Paycheck Protection Program [Member] \| Loans Range Four [Member]
Processing fee of SBA loans (percent)	1.00%
Paycheck Protection Program [Member] \| Second Round [Member]
Processing fees received			$ 800,000
Bank funding amount			$ 15,500,000
Bank funding number of customers \| Number			176
Number of loan applications received \| Number			193
Amount of loan applications received			$ 16,100,000
Number of loan applications approved \| Number			184
Amount of loan applications approved			$ 15,700,000
Paycheck Protection Program [Member] \| Minimum [Member]
Processing fee of SBA loans (percent)			1.00%
Paycheck Protection Program [Member] \| Minimum [Member] \| Loans Range Two [Member]
Loan principal amount	$ 50,000
Paycheck Protection Program [Member] \| Minimum [Member] \| Loans Range Three [Member]
Loan principal amount	350,000
Paycheck Protection Program [Member] \| Minimum [Member] \| Loans Range Four [Member]
Loan principal amount	$ 2,000,000
Paycheck Protection Program [Member] \| Maximum [Member]
Processing fee of SBA loans (percent)			5.00%
Paycheck Protection Program [Member] \| Maximum [Member] \| Loans Range One [Member]
Processing fee of SBA loans (percent)	50.00%
Loan principal amount	$ 50,000
Processing fee amount	2,500
Paycheck Protection Program [Member] \| Maximum [Member] \| Loans Range Two [Member]
Loan principal amount	$ 350,000