Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
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_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(iii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice4Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice5Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice6Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice7Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice8Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice9Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice10Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=bksc_ExercisePrice11Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

The following table presents information pertaining to options outstanding at December 31, 2021. (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 17.50	$ 14.89	$ 12.92	$ 11.86
Number of Options Outstanding	273,747
Weighted Average Remaining Contractual Life	8 years 1 month 17 days
Weighted Average Exercise Price of Options Outstanding	$ 17.50
Intrinsic Value of Options Outstanding	$ 4,790,485
Number of Options Exercisable	7,804
Weighted Average Exercise Price of Options Exercisable	$ 12.17
Intrinsic Value of Options Exercisable	$ 60,923
Exercise Price 1 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 9.18
Number of Options Outstanding	1,149
Weighted Average Remaining Contractual Life	6 months
Weighted Average Exercise Price of Options Outstanding	$ 9.18
Intrinsic Value of Options Outstanding	$ 10,548
Number of Options Exercisable	1,149
Weighted Average Exercise Price of Options Exercisable	$ 9.18
Intrinsic Value of Options Exercisable	$ 12,409
Exercise Price 2 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 12.26
Number of Options Outstanding	3,992
Weighted Average Remaining Contractual Life	2 years 6 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 12.26
Intrinsic Value of Options Outstanding	$ 48,942
Number of Options Exercisable	2,395
Weighted Average Exercise Price of Options Exercisable	$ 12.26
Intrinsic Value of Options Exercisable	$ 18,490
Exercise Price 3 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 12.40
Number of Options Outstanding	969
Weighted Average Remaining Contractual Life	2 years
Weighted Average Exercise Price of Options Outstanding	$ 12.40
Intrinsic Value of Options Outstanding	$ 12,016
Number of Options Exercisable	775
Weighted Average Exercise Price of Options Exercisable	$ 12.40
Intrinsic Value of Options Exercisable	$ 5,876
Exercise Price 4 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 13.05
Number of Options Outstanding	8,712
Weighted Average Remaining Contractual Life	3 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 13.05
Intrinsic Value of Options Outstanding	$ 113,692
Number of Options Exercisable	3,485
Weighted Average Exercise Price of Options Exercisable	$ 13.05
Intrinsic Value of Options Exercisable	$ 24,148
Exercise Price 5 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 15.21
Number of Options Outstanding	116,250
Weighted Average Remaining Contractual Life	8 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 15.21
Intrinsic Value of Options Outstanding	$ 1,768,163
Weighted Average Exercise Price of Options Exercisable	$ 15.21
Exercise Price 6 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 16.73
Number of Options Outstanding	10,000
Weighted Average Remaining Contractual Life	8 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 16.73
Intrinsic Value of Options Outstanding	$ 167,300
Weighted Average Exercise Price of Options Exercisable	$ 16.73
Exercise Price 7 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 18.23
Number of Options Outstanding	32,450
Weighted Average Remaining Contractual Life	6 years 3 months
Weighted Average Exercise Price of Options Outstanding	$ 18.23
Intrinsic Value of Options Outstanding	$ 591,564
Weighted Average Exercise Price of Options Exercisable	$ 18.23
Exercise Price 8 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 19.00
Number of Options Outstanding	2,750
Weighted Average Remaining Contractual Life	8 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 19.00
Intrinsic Value of Options Outstanding	$ 52,250
Weighted Average Exercise Price of Options Exercisable	$ 19.00
Exercise Price 9 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 19.82
Number of Options Outstanding	7,225
Weighted Average Remaining Contractual Life	8 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 19.82
Intrinsic Value of Options Outstanding	$ 143,200
Weighted Average Exercise Price of Options Exercisable	$ 19.82
Exercise Price 10 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 20.04
Number of Options Outstanding	20,250
Weighted Average Remaining Contractual Life	9 years 7 months 2 days
Weighted Average Exercise Price of Options Outstanding	$ 20.04
Intrinsic Value of Options Outstanding	$ 405,810
Weighted Average Exercise Price of Options Exercisable	$ 20.04
Exercise Price 11 Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price	$ 21.10
Number of Options Outstanding	70,000
Weighted Average Remaining Contractual Life	9 years 3 months 29 days
Weighted Average Exercise Price of Options Outstanding	$ 21.10
Intrinsic Value of Options Outstanding	$ 1,477,000
Weighted Average Exercise Price of Options Exercisable	$ 21.10