| Document And Entity Information | Nov. 13, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 13, 2024 |
| Entity Registrant Name | A-Mark Precious Metals, Inc. |
| Entity Central Index Key | 0001591588 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-36347 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 11-2464169 |
| Entity Address, Address Line One | 2121 Rosecrans Ave, Suite 6300 |
| Entity Address, City or Town | El Segundo |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90245 |
| City Area Code | (310) |
| Local Phone Number | 587-1477 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | AMRK |
| Security Exchange Name | NASDAQ |
