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Goodwill and Other Intangible Assets - Summary of the Key Characteristics, Inputs, and Economic Assumptions Used to Estimate the Fair Value of the Company's MSRs (Detail) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Bank Servicing Fees $ 196,000,000us-gaap_ServicingFeesNet $ 87,000,000us-gaap_ServicingFeesNet $ 260,000,000us-gaap_ServicingFeesNet
Servicing Asset at Fair Value, Amount 1,206,000,000us-gaap_ServicingAssetAtFairValueAmount 1,300,000,000us-gaap_ServicingAssetAtFairValueAmount  
Mortgage Servicing Rights, Fair Value [Member]      
Prepayment rate assumption (annual) 11.00%us-gaap_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 8.00%us-gaap_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Decline in fair value from 10% adverse change 46,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 38,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Decline in fair value from 20% adverse change 88,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf20PercentAdverseChangeInPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 74,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf20PercentAdverseChangeInPrepaymentSpeed
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Discount rate (annual) 10.00%us-gaap_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 [1] 12.00%us-gaap_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 [1]  
Decline in fair value from 10% adverse change 55,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 66,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Decline in fair value from 20% adverse change 105,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf20PercentAdverseChangeInDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 126,000,000us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf20PercentAdverseChangeInDiscountRate
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Weighted-average life (in years) 7 years 1 month 7 years 8 months  
Weighted-average coupon 4.20%sti_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesWeightedAverageCoupon
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		 4.40%sti_AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesWeightedAverageCoupon
/ us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis
= sti_MortgageServicingRightsFairValueMember		  
Mortgage Servicing Rights, Fair Value [Member]      
Principal Amount Outstanding of Loans Serviced For Third Parties 115,500,000,000sti_PrincipalAmountOutstandingOfLoansServicedForThirdParties
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 106,800,000,000sti_PrincipalAmountOutstandingOfLoansServicedForThirdParties
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		  
Principal Amount Sold on Loans Serviced for Third Parties 878,000,000sti_PrincipalAmountSoldonLoansServicedforThirdParties
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 2,800,000,000sti_PrincipalAmountSoldonLoansServicedforThirdParties
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		  
Bank Servicing Fees 329,000,000us-gaap_ServicingFeesNet
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 317,000,000us-gaap_ServicingFeesNet
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 333,000,000us-gaap_ServicingFeesNet
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember
Servicing Asset at Fair Value, Amount 1,206,000,000us-gaap_ServicingAssetAtFairValueAmount
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 1,300,000,000us-gaap_ServicingAssetAtFairValueAmount
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 899,000,000us-gaap_ServicingAssetAtFairValueAmount
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember
Principal Amount Outstanding Underlying MSRs Purchased $ 10,900,000,000sti_UnpaidPrincipalBalanceofOutstandingUnderlyingMSRsPurchased
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		 $ 0sti_UnpaidPrincipalBalanceofOutstandingUnderlyingMSRsPurchased
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= sti_MortgageServicingRightsFairValueMember		  
[1] 1 Option adjusted spread was a key assumption used to estimate the fair value of the Company's MSRs at December 31, 2014. At December 31, 2013, a discount rate was used.