| Document and Entity Information | Feb. 18, 2021 |
| Cover [Abstract] | |
| Security 12b Title | Common Stock — $1 par value |
| Amendment Flag | false |
| Entity Central Index Key | 0000064040 |
| Document Type | 8-K |
| Document Period End Date | Feb. 18, 2021 |
| Entity Registrant Name | S&P Global Inc. |
| Entity Incorporation State Country Code | NY |
| Entity File Number | 1-1023 |
| Entity Tax Identification Number | 13-1026995 |
| Entity Address, Address Line One | 55 Water Street |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10041 |
| City Area Code | (212) |
| Local Phone Number | 438-1000 |
| Written Communications | true |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Trading Symbol | SPGI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
