Recent Accounting and Regulatory Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Jun. 30, 2018
ASU 2018- 02 \| Early adoption
Reclassified to retained earnings from AOCI	$ 2.9
ASU 2016- 02 \| If adopted
Right to use asset		$ 78.0
Lease liabilities		$ 78.0

Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017.

No definition available.

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Namespace Prefix:	ssb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration