| Document and Entity Information | Jan. 26, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 26, 2021 |
| Entity Registrant Name | UMB FINANCIAL CORP |
| Entity Central Index Key | 0000101382 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-38481 |
| Entity Incorporation State or Country Code | MO |
| Entity Tax Identification Number | 43-0903811 |
| Entity Address, Address Line One | 1010 Grand Blvd. |
| Entity Address, City or Town | Kansas City |
| Entity Address, State or Province | MO |
| Entity Address, Postal Zip Code | 64106 |
| City Area Code | 816 |
| Local Phone Number | 860-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $1.00 Par Value |
| Trading Symbol | UMBF |
| Security Exchange Name | NASDAQ |
