| Document and Entity Information | Jun. 08, 2021 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | II-VI INC |
| Entity Incorporation State Country Code | PA |
| Amendment Flag | false |
| Entity Central Index Key | 0000820318 |
| Document Type | 8-K |
| Document Period End Date | Jun. 8, 2021 |
| Entity File Number | 001-39375 |
| Entity Tax Identification Number | 25-1214948 |
| Entity Address, Address Line One | 375 Saxonburg Boulevard |
| Entity Address, City or Town | Saxonburg |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 16056 |
| City Area Code | (724) |
| Local Phone Number | 352-4455 |
| Written Communications | true |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, no par value |
| Trading Symbol | IIVI |
| Security Exchange Name | NASDAQ |
| Series A Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Series A Mandatory Convertible Preferred Stock, no par value |
| Trading Symbol | IIVIP |
| Security Exchange Name | NASDAQ |
