Securities Purchased Under Agreements to Resell - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Resale Agreement Counterparty [Line Items]
Collateral percentage of underlying securities, minimum	95.00%
Collateral percentage of underlying securities, maximum	110.00%
Market value of collateral securities	$ 806	$ 1,100
Market value of collateral securities, repledged	$ 247	$ 165

Collateral Requirements Maximum Percentage Collateral To Fair Value Of Securities Loaned Or Purchased Under Repurchase Agreements

No definition available.

+ Details

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

- Definition

Collateral Requirements, Minimum Percentage, Collateral To Fair Value Of Securities Loaned Or Purchased Under Repurchase Agreements

+ References

No definition available.

+ Details

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

- Definition

This is the fair value as of the date of each statement of financial position presented of the collateral that is permitted, by contact or custom, to be sold or re-pledged.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph a(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6862952&loc=SL6224234-111729

+ Details

Name:	us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatCanBeResoldOrRepledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used (generally under repurchase agreements, securities lending agreements or to cover short sales).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=6862952&loc=SL6224234-111729

+ Details

Name:	us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatHaveBeenResoldOrRepledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_ResaleAgreementCounterpartyLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration