| Document and Entity Information Document | Jul. 18, 2019 | Jun. 30, 2019 |
| Document Information [Line Items] | ||
| Amendment Flag | false | |
| Entity Registrant Name | SUNTRUST BANKS INC | |
| Document Period End Date | Jul. 18, 2019 | |
| Document Type | 8-K | |
| Entity Incorporation, State or Country Code | 2Q | |
| Entity File Number | 001-08918 | |
| Entity Tax Identification Number | 58-1575035 | |
| Written Communications | true | |
| 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 | |
| Entity Emerging Growth Company | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Trading Symbol | STI | |
| Security Exchange Name | NYSE | |
| Title of 12(b) Security | Common Stock | |
| Preferred Class A [Member] | NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Trading Symbol | STI PRA | |
| Security Exchange Name | NYSE | |
| Title of 12(b) Security | Series A Preferred Stock | |
| Preferred Class B [Member] | NEW YORK STOCK EXCHANGE, INC. [Member] | ||
| Document Information [Line Items] | ||
| Trading Symbol | STI/PRI | |
| Security Exchange Name | NYSE | |
| Title of 12(b) Security | Series B Preferred Stock |
| Entity Listing Information Document - NEW YORK STOCK EXCHANGE, INC. [Member] | 6 Months Ended |
| Jun. 30, 2019 | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | STI |
| Security Exchange Name | NYSE |
| Preferred Class A [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Series A Preferred Stock |
| Trading Symbol | STI PRA |
| Security Exchange Name | NYSE |
| Preferred Class B [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Series B Preferred Stock |
| Trading Symbol | STI/PRI |
| Security Exchange Name | NYSE |
