| Document and Entity Information | Apr. 02, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Apr. 2, 2020 |
| Entity Registrant Name | CACI International Inc |
| Entity Central Index Key | 0000016058 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-31400 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 54-1345888 |
| Entity Address, Address Line One | 1100 N. Glebe Road |
| Entity Address, City or Town | Arlington |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 22201 |
| City Area Code | 703 |
| Local Phone Number | 841-7800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of each class | Common Stock |
| Trading Symbol | CACI |
| Name of each exchange on which registered | NYSE |
