Instagram oembed is created as document instead of image

I have created the following provider for Instagram:

$provider = new stdClass();
$provider->disabled = FALSE; /* Edit this to true to make a default provider disabled initially */
$provider->api_version = 1;
$provider->name = 'instagram';
$provider->title = 'instagram';
$provider->endpoint = 'http://api.instagram.com/oembed';
$provider->scheme = 'http://instagram.com/p/*
http://instagr.am/p/*
https://instagram.com/p/*
https://instagr.am/p/*';

It is working quite right so far, but I was guessing if the oembed Media File Entity could be recognized as "Image" instead of "Document".

Thanks.