If the document was intended for distribution, it is likely that any non-embedded fonts are going to be common system fonts that will either have direct replace

If the document was intended for distribution, it is likely that any non-embedded fonts are going to be common system fonts that will either have direct replacements or compatible replacements. Of course all bets are off, if someone created a document for personal use, to share with family/friends, or simply didn't know what they were doing.