| Cover | May 20, 2021 |
| Document Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000054480 |
| Document Type | 8-K |
| Document Period End Date | May 20, 2021 |
| Entity Registrant Name | KANSAS CITY SOUTHERN |
| Entity Incorporation, State or 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 | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| $25 Par Preferred Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Preferred Stock, Par Value $25 Per Share, 4%, Noncumulative |
| Trading Symbol | KSU |
| Security Exchange Name | NYSE |
| Common Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock, $.01 Per Share Par Value |
| Trading Symbol | KSU |
| Security Exchange Name | NYSE |
