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Assets and Liabilities Measured at Fair Value on a Recurring Basis (Additional Information) (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Derivative Assets $ 1,475us-gaap_DerivativeAssets [1]   $ 1,307us-gaap_DerivativeAssets [1]
Derivative Liabilities 552us-gaap_DerivativeLiabilities [2]   462us-gaap_DerivativeLiabilities [2]
Interest Rate Lock Commitments [Member]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 60us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_InvestmentTypeAxis
= us-gaap_InterestRateLockCommitmentsMember		 55us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_InvestmentTypeAxis
= us-gaap_InterestRateLockCommitmentsMember		  
Federal Reserve Bank Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]      
Investments, Fair Value Disclosure 402us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= sti_FederalReserveBankStockMember		   402us-gaap_InvestmentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= sti_FederalReserveBankStockMember
Long-term Debt [Member] | Fair Value, Inputs, Level 2 [Member]      
Fair Value, Option, Credit Risk, Gains (Losses) on Liabilities 4us-gaap_FairValueOptionCreditRiskGainsLossesOnLiabilities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_LongTermDebtMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 (17)us-gaap_FairValueOptionCreditRiskGainsLossesOnLiabilities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_LongTermDebtMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		  
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member]      
Asset Impairment Charges 0us-gaap_AssetImpairmentCharges
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherAssetsMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember		   64us-gaap_AssetImpairmentCharges
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherAssetsMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Other Assets [Member] | Property Subject to Operating Lease [Member] | Fair Value, Measurements, Nonrecurring [Member]      
Asset Impairment Charges     $ 59us-gaap_AssetImpairmentCharges
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherAssetsMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_PropertySubjectToOperatingLeaseMember
[1] At March 31, 2015, $1.5 billion, net of $530 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2014, $1.3 billion, net of $449 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.
[2] At March 31, 2015, $552 million, net of $1.1 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2014, $462 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.