SHORT-TERM AND LONG -TERM DEBT (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($)
Fixed Rate Credit One [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Maturity Date	Feb. 02, 2021
Fixed Rate Credit Two [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Maturity Date	Apr. 12, 2023
Fixed Rate Credit Three [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Maturity Date	May 30, 2023
Fixed Rate Credit Four [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Maturity Date	Jun. 28, 2023
Federal Home Loan Bank of Atlanta [Member] \| Fixed Rate Credit One [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Amount	$ 20,000
Advance type, Rate	2.53%
Federal Home Loan Bank of Atlanta [Member] \| Fixed Rate Credit Two [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Amount	$ 10,000
Advance type, Rate	2.89%
Federal Home Loan Bank of Atlanta [Member] \| Fixed Rate Credit Three [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Amount	$ 5,000
Advance type, Rate	2.94%
Federal Home Loan Bank of Atlanta [Member] \| Fixed Rate Credit Four [Member]
Short Term And Long Term Debt [Line Items]
Advance type, Amount	$ 10,000
Advance type, Rate	2.97%

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.

No definition available.

+ Details

Name:	slct_ShortTermAndLongTermDebtLineItems
Namespace Prefix:	slct_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of advances from the Federal Home Loan Bank (FHLB).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

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

- Definition

Discloses the single interest rate [if] applicable to the advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=slct_FixedRateCreditOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=slct_FixedRateCreditTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=slct_FixedRateCreditThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=slct_FixedRateCreditFourMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfAtlantaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: