Components of Net Periodic Benefit Cost (parenthetical) (Details) (Pension Plans, Defined Benefit)	Dec. 31, 2012	Nov. 15, 2011	Nov. 14, 2011
Pension Plans, Defined Benefit
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical	7.00%	7.25%	7.75%

Defined Benefit Plan, Basis Used to Determine Overall Expected Long Term Rate of Returns on Assets Assumption, Historical

No definition available.

Name:	sti_DefinedBenefitPlanBasisUsedToDetermineOverallExpectedLongTermRateOfReturnsOnAssetsAssumptionHistorical
Namespace Prefix:	sti_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant