| Document and Entity Information | Dec. 03, 2020 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | ON SEMICONDUCTOR CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0001097864 |
| Document Type | 8-K |
| Document Period End Date | Dec. 3, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-39317 |
| Entity Tax Identification Number | 36-3840979 |
| Entity Address, Address Line One | ON Semiconductor Corporation |
| Entity Address, Address Line Two | 5005 E. McDowell Road |
| Entity Address, City or Town | Phoenix |
| Entity Address, State or Province | AZ |
| Entity Address, Postal Zip Code | 85008 |
| City Area Code | (602) |
| Local Phone Number | 244-6600 |
| Written Communications | false |
| 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, par value $0.01 per share |
| Trading Symbol | ON |
| Security Exchange Name | NASDAQ |
| Series B Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Preferred Stock, Series B Junior Participating, Purchase Rights |
| Security Exchange Name | NASDAQ |
