| Cover Page | Sep. 02, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 2, 2020 |
| Entity Registrant Name | SPX CORP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-6948 |
| Entity Tax Identification Number | 38-1016240 |
| Entity Address, Address Line One | 6325 Ardrey Kell Road |
| Entity Address, Address Line Two | Suite 400 |
| Entity Address, City or Town | Charlotte |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 28277 |
| City Area Code | 980 |
| Local Phone Number | 474-3700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.01 |
| Trading Symbol | SPXC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000088205 |
| Amendment Flag | false |
