| Document and Entity Information Document | Oct. 17, 2019 | |
| Document Information [Line Items] | ||
| Amendment Flag | false | |
| Entity Registrant Name | SunTrust Banks Inc | |
| Document Period End Date | Oct. 17, 2019 | |
| Document Type | 8-K | |
| Entity Incorporation, State or Country Code | GA | |
| Entity File Number | 001-08918 | |
| Entity Tax Identification Number | 58-1575035 | |
| Entity Address, Address Line One | 303 Peachtree Street, N.E., | |
| Entity Address, City or Town | Atlanta, | |
| Entity Address, State or Province | GA | |
| Entity Address, Postal Zip Code | 30308 | |
| City Area Code | (800) | |
| Local Phone Number | 786-8787 | |
| Entity Central Index Key | 0000750556 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Common Stock | |
| Trading Symbol | STI | |
| Security Exchange Name | NYSE | |
| Preferred Class A [Member] | NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Perpetual Preferred Stock, Series A | [1] |
| Trading Symbol | STI PRA | |
| Security Exchange Name | NYSE | |
| Preferred Class B [Member] | NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Perpetual Preferred Stock, Series B | [2] |
| Trading Symbol | STI/PRI | |
| Security Exchange Name | NYSE | |
| [1] | Depositary Shares, Each Representing a 1/4000 th Interest in a Share of Perpetual Preferred Stock, Series A . | |
| [2] | 5.853% Fixed-to-Floating Rate Normal Preferred Purchase Securities of SunTrust Preferred Capital I (representing interests in shares of Perpetual Preferred Stock, Series B) . | |
