| Document and Entity Information | May 21, 2021 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000054480 |
| Document Type | 8-K |
| Document Period End Date | May 21, 2021 |
| Entity Registrant Name | KANSAS CITY SOUTHERN |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-4717 |
| Entity Tax Identification Number | 44-0663509 |
| Entity Address, Address Line One | 427 West 12th Street |
| Entity Address, City or Town | Kansas City |
| Entity Address, State or Province | MO |
| Entity Address, Postal Zip Code | 64105 |
| City Area Code | (816) |
| Local Phone Number | 983-1303 |
| Written Communications | true |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Preferred Stock, Par Value $25 Per Share, 4%, Noncumulative |
| Trading Symbol | KSU |
| Security Exchange Name | NYSE |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, $.01 Per Share Par Value |
| Trading Symbol | KSU |
| Security Exchange Name | NYSE |
