Loans - Changes in Status of Loans (Details) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) loan
Loans Designated as TDRs
Paying under restructured terms - Number of Loans \| loan	26
Paying under restructured terms - Amortized Cost \| $	$ 3,692
Converted to Nonaccrual - Number of Loans \| loan	2
Converted to Nonaccrual - Amortized Cost \| $	$ 1,349
Interest rate modification
Loans Designated as TDRs
Paying under restructured terms - Number of Loans \| loan	17
Paying under restructured terms - Amortized Cost \| $	$ 2,787
Converted to Nonaccrual - Number of Loans \| loan	2
Converted to Nonaccrual - Amortized Cost \| $	$ 1,349
Term modification
Loans Designated as TDRs
Paying under restructured terms - Number of Loans \| loan	9
Paying under restructured terms - Amortized Cost \| $	$ 905

Number of financing receivables that have been modified by troubled debt restructurings and converted to nonaccrual.

No definition available.

Name:	ssb_FinancingReceivableModificationsNumberOfContractsConvertedToNonaccrual
Namespace Prefix:	ssb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings and paying under restructured terms.

+ References

No definition available.

+ Details

Name:	ssb_FinancingReceivableModificationsNumberOfContractsUnderRestructuredTerms
Namespace Prefix:	ssb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable converted to nonaccrual.

+ References

No definition available.

+ Details

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

- Definition

Amount, after troubled debt restructuring, of modified financing receivable under restructured terms.

+ References

No definition available.

+ Details

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

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: