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

No definition available.

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- 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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- 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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- Definition

Defined Contribution Plan Employer Discretionary Matching Contribution Percent

+ References

No definition available.

+ Details

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Namespace Prefix:	ssb_
Data Type:	xbrli:pureItemType
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- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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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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
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- Details

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Namespace Prefix:
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- Details

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Retirement Plans - Safe Harbor plan - (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2018 USD ($)	Mar. 31, 2018	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2018	Dec. 31, 2017
Employees' savings plan
Matching contribution by the company (as a percent)						100.00%	100.00%
Discretionary matching contribution		1				2	1
Expenses recognized under 401(K) plan	$ 1.8		$ 2.1	$ 5.1	$ 5.5
Minimum
Employees' savings plan
Age of employees to be eligible to participate in the defined contribution plan				21 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						4.00%	5.00%