Commitments and Contingent Liabilities (Details) $ in Millions	Mar. 31, 2020 USD ($)
Commitments and Contingent Liabilities
Commitments to extend credit and standby letters of credit	$ 3,000.0
Liability Recorded for Expected Credit Losses on Unfunded Commitments	$ 8.6

The total amount outstanding of the commitments to extend credit and standby letters of credit as of the reporting date.

No definition available.

Name:	ssb_CommitmentsToExtendCreditAndStandbyLettersOfCredit
Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant