| Cover Page | Jun. 14, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 14, 2021 |
| Entity Registrant Name | IDEX CORP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-10235 |
| Entity Tax Identification Number | 36-3555336 |
| Entity Address, Address Line One | 3100 Sanders Road |
| Entity Address, Address Line Two | Suite 301 |
| Entity Address, City or Town | Northbrook |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60062 |
| City Area Code | 847 |
| Local Phone Number | 498-7070 |
| 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 $.01 per share |
| Trading Symbol | IEX |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000832101 |
| Amendment Flag | false |
