The following code works fine in FF:
var date = new Date();
date.setTime(date.getTime() + (1 * 24 * 60 * 60 * 1000));
expires = \"; expires=\" + date.toGMTSt
Seems like it's working for me:

http://jsfiddle.net/rQEnF/3/
At least the cookie shows up in dev tools, as you can see. However, I replaced the jQuery selector $('#orderdetailid').val() with a constant value, as you can see. Is there something wrong with that value or the element containing the value maybe?