Amount of uninsured deposits adjusted to exclude over assessment periods.

No definition available.

Name:	ssb_AmountOfUninsuredDepositsAdjustedToExclude
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The total amount outstanding of the commitments to extend credit and standby letters of credit as of the reporting date.

No definition available.

Name:	ssb_CommitmentsToExtendCreditAndStandbyLettersOfCredit
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of additional expense for Federal Deposit Insurance Corporation (FDIC) special assessment.

No definition available.

Name:	ssb_FederalDepositInsuranceCorporationSpecialAssessmentAdditionalExpense
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of expense for Federal Deposit Insurance Corporation (FDIC) special assessment.

No definition available.

Name:	ssb_FederalDepositInsuranceCorporationSpecialAssessmentExpense
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of liability recorded for expected credit losses on unfunded commitments.

No definition available.

Name:	ssb_LiabilityRecordedForExpectedCreditLossesOnUnfundedCommitments
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Period for special assessment.

No definition available.

Name:	ssb_SpecialAssessmentPeriod
Namespace Prefix:	ssb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Percentage of base annual rate of uninsured deposits.

No definition available.

Name:	ssb_UninsuredDepositsBaseAnnualRate
Namespace Prefix:	ssb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

No definition available.

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

Commitments and Contingent Liabilities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2024	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingent Liabilities
Commitments to extend credit and standby letters of credit		$ 9,000.0
Liability recorded for expected credit losses on unfunded commitments		41.5
FDIC base annual rate	13.40%
Amount of uninsured deposits adjusted to exclude over assessment periods			$ 25.7	$ 5,000.0
Period for special assessment			2 years
FDIC special assessment additional expense		4.5
FDIC special assessment		$ 30.2