Custom Plugin remove ?id= from details page url

I have a custom plugin that has a directory search. I pass the url to the details page and output the results. I am trying to format the URL to be 'pretty' on the details page :

FROM: /membership-directory/details/?id=xxxxxxx

TO: /membership-directory/details/xxxxxx

Digging all over to find the proper way to do this. Can somebody direct me to some examples of what is the best way to handle this?

via Chebli Mohamed