While TransMagic does not support the I-DEAS application natively, it does support several formats that I-DEAS does. I-DEAS can read/write both Parasolid *.x_t and JT *.jt files and so can TransMagic. So if you can obtain a *.x_t or *.jt file from I-DEAS then you can use these formats in TransMagic to interoperate with I-DEAS.
Also, keep in mind that the most common I-DEAS native file is *.prt. Coincidentally the *.prt file extension is used by many CAD systems such as UG NX, KeyCreator (formerly CADKEY), and several others. If you have a *.prt file that TransMagic won't read you can submit it to TransMagic Support by clicking the "Support" Tab and then "Request Support". We can tell you if the file is an I-DEAS file or a UG NX file.