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:	num: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

Name:	ssb_DefinedContributionPlanEmployerContributionPercent
Namespace Prefix:	ssb_
Data Type:	num: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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Retirement Plans - Safe Harbor plan - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employees' savings plan
Matching contribution by the company (as a percent)	100.00%
Expenses recognized under 401(K) plan	$ 7,381	$ 6,178	$ 5,873
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	50.00%
Percentage of employees salary for which the company contributes a matching contribution	5.00%