Same page or different page is really dependent upon the details themselves.
details are something like 20 numbers... you could do a simple table with show/hide jquery on the same page.
details are 20 different paragraphs of information then a page may be more feasible.
The determining factor would be how cumbersome seeing all the extra data is to the user.
If ingesting the extra data requires time and a user may need to refer to it multiple times to "get" it all, then you may want to displayed on its own.
If the nature of the
details are brief, quick info, such as contact information, then the same page may work best. Primarily because the
details would be something a user may need to quickly refer to then dismiss. If there's no cause to spend a great deal of time looking at the extra information, then an easy way to see it, then hide it is often more user-friendly.