Cover Page
| Cover Page | Nov. 10, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 10, 2020 |
| Entity Registrant Name | GRAHAM HOLDINGS CO |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-06714 |
| Entity Tax Identification Number | 53-0182885 |
| Entity Address, Address Line One | 1300 North 17th Street |
| Entity Address, City or Town | Arlington |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 22209 |
| City Area Code | 703 |
| Local Phone Number | 345-6300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class B Common Stock, par value $1.00 per share |
| Trading Symbol | GHC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000104889 |
| Amendment Flag | false |