| Document and Entity Information | Dec. 04, 2019 |
| Cover [Abstract] | |
| Entity Registrant Name | Madison Square Garden Co |
| Entity Address, State or Province | NY |
| Amendment Flag | false |
| Entity Central Index Key | 0001636519 |
| Current Fiscal Year End Date | --06-30 |
| Document Type | 8-K |
| Document Period End Date | Dec. 4, 2019 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-36900 |
| Entity Tax Identification Number | 47-3373056 |
| Entity Address, Address Line One | 2 Penn Plaza |
| Entity Address, City or Town | New York |
| Entity Address, Postal Zip Code | 10121 |
| City Area Code | (212) |
| Local Phone Number | 465-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A Common Stock |
| Trading Symbol | MSG |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
