| 8-K Cover Page | Oct. 20, 2020 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 20, 2020 |
| Entity Registrant Name | SYNCHRONY FINANCIAL |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36560 |
| Entity Tax Identification Number | 51-0483352 |
| Entity Address, Address Line One | 777 Long Ridge Road |
| Entity Address, City or Town | Stamford, |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06902 |
| City Area Code | 203 |
| Local Phone Number | 585-2400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001601712 |
| Common Stock | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Common stock, par value $0.001 per share |
| Trading Symbol | SYF |
| Security Exchange Name | NYSE |
| Series A Preferred Stock | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares Each Representing a 1/40th Interest in a Share of 5.625% Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series A |
| Trading Symbol | SYFPrA |
| Security Exchange Name | NYSE |
