Represents the age of employees to be eligible to participate in the defined contribution plan.

No definition available.

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

- Definition

Represents employee contributions to a defined contribution pension plan as a percentage of annual base compensation.

+ References

No definition available.

+ Details

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

- Definition

The percentage of the employee contribution for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

Name:	ssb_ScheduleOfDefinedContributionBenefitPlansDisclosuresLineItems
Namespace Prefix:	ssb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480794/715-70-50-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Retirement Plans (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Employees' savings plan
Matching contribution by the company (as a percent)			100.00%
Employee savings plan	$ 4.3	$ 4.0	$ 13.3	$ 12.7
Minimum
Employees' savings plan
Age of employees to be eligible to participate in the defined contribution plan			18 years
Percentage of annual base compensation that participants may elect to contribute			1.00%
Maximum
Employees' savings plan
Percentage of annual base compensation that participants may elect to contribute			85.00%
Percentage of employees salary for which the company contributes a matching contribution			4.00%