Loans and Allowance for Loan Losses - Nonaccrual loans - (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	$ 77,648	$ 35,079
Recorded Investment With No Allowance	10,985	7,736
Gross Recorded Investment With Allowance	52,438	13,475
Total Recorded Investment	63,423	21,211
Related Allowance	1,624	1,337
Average Investment In Impaired Loans	42,318	25,715	$ 28,651
Interest Income Recognized	1,984	913	1,216
Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	14,340	14,464
Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	9,397	4,728
Commercial non-owner occupied real estate \| Construction and land development
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	47,553	7,394
Recorded Investment With No Allowance	649	1,074
Gross Recorded Investment With Allowance	42,581	1,959
Total Recorded Investment	43,230	3,033
Related Allowance	1,063	348
Average Investment In Impaired Loans	23,132	4,657	5,566
Interest Income Recognized	1,138	120	263
Commercial non-owner occupied real estate \| Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,106	2,417
Recorded Investment With No Allowance	860	223
Gross Recorded Investment With Allowance	515	583
Total Recorded Investment	1,375	806
Related Allowance	125	170
Average Investment In Impaired Loans	1,091	1,129	2,531
Interest Income Recognized	45	32	66
Commercial non-owner occupied real estate \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,886	1,250
Commercial non-owner occupied real estate \| Non acquired non-accrual loans \| Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	251	672
Commercial non-owner occupied real estate \| Non acquired non-accrual loans \| Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Nonaccrual loans	2,635	578
Commercial non-owner occupied real estate \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	108	232
Commercial non-owner occupied real estate \| Acquired non-credit impaired non-accrual loans \| Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	108	232
Commercial owner occupied real estate loan
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	9,212	10,118
Recorded Investment With No Allowance	3,553	3,976
Gross Recorded Investment With Allowance	2,089	2,269
Total Recorded Investment	5,642	6,245
Related Allowance	64	67
Average Investment In Impaired Loans	5,943	6,985	8,442
Interest Income Recognized	268	291	368
Commercial owner occupied real estate loan \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,144	2,189
Commercial owner occupied real estate loan \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	189	61
Consumer real estate \| Home equity loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,602	2,165
Recorded Investment With No Allowance	896	244
Gross Recorded Investment With Allowance	2,115	1,430
Total Recorded Investment	3,011	1,674
Related Allowance	135	40
Average Investment In Impaired Loans	2,343	992	170
Interest Income Recognized	113	61	10
Consumer real estate \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	7,382	7,090
Recorded Investment With No Allowance	4,392	2,120
Gross Recorded Investment With Allowance	1,240	3,553
Total Recorded Investment	5,632	5,673
Related Allowance	37	80
Average Investment In Impaired Loans	5,653	6,611	5,257
Interest Income Recognized	195	206	183
Consumer real estate \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	5,157	7,340
Consumer real estate \| Non acquired non-accrual loans \| Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	269	1,629
Consumer real estate \| Non acquired non-accrual loans \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	4,888	5,711
Consumer real estate \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	6,745	3,048
Consumer real estate \| Acquired non-credit impaired non-accrual loans \| Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	4,589	1,643
Consumer real estate \| Acquired non-credit impaired non-accrual loans \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,156	1,405
Commercial and industrial
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	2,246	2,335
Recorded Investment With No Allowance	635
Gross Recorded Investment With Allowance	521	1,263
Total Recorded Investment	1,156	1,263
Related Allowance	15	386
Average Investment In Impaired Loans	1,209	1,375	1,198
Interest Income Recognized	48	52	61
Commercial and industrial \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,662	420
Commercial and industrial \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	133	1
Other income producing property
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,893	3,166
Recorded Investment With No Allowance		99
Gross Recorded Investment With Allowance	3,138	2,273
Total Recorded Investment	3,138	2,372
Related Allowance	178	242
Average Investment In Impaired Loans	2,755	3,632	5,195
Interest Income Recognized	171	145	245
Other income producing property \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	764	356
Other income producing property \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	316	145
Consumer
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	654	394
Gross Recorded Investment With Allowance	239	145
Total Recorded Investment	239	145
Related Allowance	7	4
Average Investment In Impaired Loans	192	123	81
Interest Income Recognized	6	6	4
Consumer \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,802	930
Consumer \| Acquired non-credit impaired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 1,906	1,241
Other loans
Loans and Allowance for Loan Losses
Average Investment In Impaired Loans		211	211
Interest Income Recognized			$ 16
Restructured loans \| ASC Topic 31020 Loans \| Minimum
Loans and Allowance for Loan Losses
Number of months generally required to return to accruing status	6 months
Restructured loans \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 925	$ 1,979

Nonaccrual TDRs are returned to accruing status after demonstrated sustained repayment performance.

No definition available.

Name:	ssb_LengthOfTimeWithSustainedRepaymentPerformanceToReturnToAccruingStatus
Namespace Prefix:	ssb_
Data Type:	xbrli:durationItemType
Balance Type:	na
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_FinancingReceivableImpairedLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=ssb_NonAcquiredNonAccrualLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=ssb_AcquiredNonCreditImpairedNonAccrualLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_CommercialNonOwnerOccupiedRealEstateLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ssb_OtherCommercialNonOwnerOccupiedRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_CommercialOwnerOccupiedRealEstateLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ssb_ConsumerOwnerOccupiedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_CommercialAndIndustrialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_OtherIncomeProducingPropertyLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_ConsumerLoansPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_OtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ssb_RestructuredLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=ssb_AccountingStandardCodificationTopic31020LoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: