| Cover | May 14, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | May 14, 2020 |
| Entity File Number | 001-33962 |
| Entity Registrant Name | COHERENT, INC. |
| Entity Central Index Key | 0000021510 |
| Entity Tax Identification Number | 94-1622541 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 5100 Patrick Henry Drive |
| Entity Address, City or Town | Santa Clara |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95054 |
| City Area Code | 408 |
| Local Phone Number | 764-4000 |
| 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 | COHR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
