Loans and Allowance for Loan Losses - Nonaccrual loans - (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 14,109	$ 12,958	$ 14,340
Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	80,646	41,242	77,648
Recorded Investment With No Allowance	10,591	7,585	10,985
Gross Recorded Investment With Allowance	56,105	19,738	52,438
Total Recorded Investment	66,696	27,323	63,423
Related Allowance	1,712	1,658	1,624
Average Investment In Impaired Loans	65,061	24,267
Interest Income Recognized	728	241
Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	8,076	4,915	9,397
Commercial non-owner occupied real estate \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,674	2,273	2,886
Commercial non-owner occupied real estate \| Non acquired non-accrual loans \| Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	500	195	251
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	1,174	2,078	2,635
Commercial non-owner occupied real estate \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 \| Construction and land development
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	50,399	13,674	47,553
Recorded Investment With No Allowance	476	1,344	649
Gross Recorded Investment With Allowance	45,722	7,942	42,581
Total Recorded Investment	46,198	9,286	43,230
Related Allowance	767	459	1,063
Average Investment In Impaired Loans	44,714	6,160
Interest Income Recognized	513	47
Commercial non-owner occupied real estate \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 \| Other commercial non-owner occupied real estate
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	2,916	2,393	3,106
Recorded Investment With No Allowance	659	218	860
Gross Recorded Investment With Allowance	522	557	515
Total Recorded Investment	1,181	775	1,375
Related Allowance	110	158	125
Average Investment In Impaired Loans	1,278	791
Interest Income Recognized	5	6
Commercial non-owner occupied real estate \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	426	229	108
Commercial non-owner occupied real estate \| Acquired non-credit impaired non-accrual including restructured loans \| Construction and land development
Loans and Allowance for Loan Losses
Nonaccrual loans	426	229	108
Commercial owner occupied real estate loan \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,647	2,905	1,144
Commercial owner occupied real estate loan \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	8,972	10,082	9,212
Recorded Investment With No Allowance	3,273	4,191	3,553
Gross Recorded Investment With Allowance	2,305	2,060	2,089
Total Recorded Investment	5,578	6,251	5,642
Related Allowance	63	60	64
Average Investment In Impaired Loans	5,610	6,248
Interest Income Recognized	75	76
Commercial owner occupied real estate loan \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	178	158	189
Consumer real estate \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	8,134	3,913	5,157
Consumer real estate \| Non acquired non-accrual loans \| Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	2,593	11	269
Consumer real estate \| Non acquired non-accrual loans \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	5,541	3,902	4,888
Consumer real estate \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 \| Home equity loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,855	2,962	3,602
Recorded Investment With No Allowance	1,105	252	896
Gross Recorded Investment With Allowance	2,063	2,180	2,115
Total Recorded Investment	3,168	2,432	3,011
Related Allowance	73	297	135
Average Investment In Impaired Loans	3,090	2,053
Interest Income Recognized	29	20
Consumer real estate \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20 \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	7,245	6,084	7,382
Recorded Investment With No Allowance	4,332	1,483	4,392
Gross Recorded Investment With Allowance	1,161	3,229	1,240
Total Recorded Investment	5,493	4,712	5,632
Related Allowance	35	68	37
Average Investment In Impaired Loans	5,563	5,192
Interest Income Recognized	43	39
Consumer real estate \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	5,358	3,237	6,745
Consumer real estate \| Acquired non-credit impaired non-accrual including restructured loans \| Home equity loans
Loans and Allowance for Loan Losses
Nonaccrual loans	3,931	1,784	4,589
Consumer real estate \| Acquired non-credit impaired non-accrual including restructured loans \| Consumer Owner Occupied Loans
Loans and Allowance for Loan Losses
Nonaccrual loans	1,427	1,453	2,156
Commercial and industrial \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	799	473	1,662
Commercial and industrial \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	2,679	2,419	2,246
Recorded Investment With No Allowance	634		635
Gross Recorded Investment With Allowance	1,043	1,270	521
Total Recorded Investment	1,677	1,270	1,156
Related Allowance	489	387	15
Average Investment In Impaired Loans	1,417	1,266
Interest Income Recognized	17	18
Commercial and industrial \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	138		133
Other income producing property \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	170	1,316	764
Other income producing property \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	3,793	3,153	3,893
Recorded Investment With No Allowance	112	97
Gross Recorded Investment With Allowance	2,974	2,311	3,138
Total Recorded Investment	3,086	2,408	3,138
Related Allowance	166	224	178
Average Investment In Impaired Loans	3,112	2,390
Interest Income Recognized	46	35
Other income producing property \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	325	83	316
Consumer \| Non acquired non-accrual loans
Loans and Allowance for Loan Losses
Nonaccrual loans	903	1,029	1,802
Consumer \| Impaired non-acquired and acquired loans accounted under FASB ASC topic 310-20
Loans and Allowance for Loan Losses
Unpaid Contractual Principal Balance	787	475	654
Gross Recorded Investment With Allowance	315	189	239
Total Recorded Investment	315	189	239
Related Allowance	9	5	7
Average Investment In Impaired Loans	277	167
Consumer \| Acquired non-credit impaired non-accrual including restructured loans
Loans and Allowance for Loan Losses
Nonaccrual loans	$ 1,651	1,208	1,906
Restructured loans \| ASC Topic 31020 Loans
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	$ 782	$ 1,049	$ 925

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_ImpairedNonAcquiredAndAcquiredLoansAccountedUnderFasbAscTopic31020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=ssb_AcquiredNonCreditImpairedNonAccrualIncludingRestructuredLoansMember
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_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: