| Cover | Aug. 02, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 02, 2022 |
| Entity Registrant Name | Oak Street Health, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39427 |
| Entity Tax Identification Number | 84-3446686 |
| Entity Address, Address Line One | 30 W. Monroe Street |
| Entity Address, Address Line Two | Suite 1200 |
| Entity Address, City or Town | Chicago |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60603 |
| City Area Code | 844 |
| Local Phone Number | 871-5650 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value |
| Trading Symbol | OSH |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001564406 |
| Amendment Flag | false |
