jQuery $.each() - Array of Objects

I am trying to perform jQuery each function on something like:

"RelatedDoc": [
    {
        "Id": "test",
        "Number": "26262316"
    }
],

Which is a part of a large JSON object. So far I have:

$.each($('#panel_MRD').data('obj'), function (key,value) {
    $('select.mrdDisplayBox').addOption( key, value, false);
});

I am trying to get the option to display "ID - NUMBER" - Any ideas? The above displays but not the right format.