| Document and Entity Information | Sep. 22, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | MARRIOTT INTERNATIONAL INC /MD/ |
| Amendment Flag | false |
| Entity Central Index Key | 0001048286 |
| Document Type | 8-K |
| Document Period End Date | Sep. 22, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-13881 |
| Entity Tax Identification Number | 52-2055918 |
| Entity Address, Address Line One | 10400 Fernwood Road |
| Entity Address, City or Town | Bethesda |
| Entity Address, State or Province | MD |
| Entity Address, Postal Zip Code | 20817 |
| City Area Code | (301) |
| Local Phone Number | 380-3000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A Common Stock, $0.01 par value |
| Trading Symbol | MAR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
