Mortgage Loan Servicing, Origination, and Loans Held for Sale - Mandatory cash forwards (Details) - USD ($)	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Mortgage loan securitizations, mandatory cash forwards, and whole loan sales
Repurchase of principal balance	$ 117,000,000,000	$ 345,000,000,000
Loan sales	222,600,000	159,400,000
Loan securitizations and loan sales	$ 160,700,000	$ 123,000,000.0
Percentage of loan securitizations and loan sales	72.20%	77.20%
Loss reimbursement and settlement claims paid	$ 9,000	$ 11,000
Loans held for sale	$ 56,553,000		$ 50,888,000
Residential mortgage loans awaiting sale in secondary market \| Minimum
Mortgage loan securitizations, mandatory cash forwards, and whole loan sales
Loans held for sale, settlement period	15 days
Residential mortgage loans awaiting sale in secondary market \| Maximum
Mortgage loan securitizations, mandatory cash forwards, and whole loan sales
Loans held for sale, settlement period	45 days

The amount of cash paid for the loss reimbursement and settlement.

No definition available.

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- Definition

Represent the settlement period of loan held for sale.

+ References

No definition available.

+ Details

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- Definition

Represents the loans repurchased.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of mortgage loan securitized and sold during the period.

+ References

No definition available.

+ Details

Name:	ssb_MortgageLoanSecuritizationsAndSales
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Represents the amount of mortgage loan sold during the period.

+ References

No definition available.

+ Details

Name:	ssb_MortgageLoanSold
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the percentage of mortgage loan securitized and sold during the period with servicing rights retained by the company.

+ References

No definition available.

+ Details

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Namespace Prefix:	ssb_
Data Type:	dtr-types:percentItemType
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Period Type:	duration

- Definition

Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481852/948-310-45-1

+ Details

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Balance Type:	debit
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- Details

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- Details

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