Correct me if I'm wrong, but 通訳 is used for translating conversations(interpreting) whereas 翻訳 is used more for translating documents, right? I have a document that I had a Japanese friend translate verbally. Would that be 通訳 or 翻訳？ Or maybe another word I haven't heard of?
Technically, that is called サイトトランスレーション, which is how "sight translation" is katakanized. If you were expecting a kanji word, I do not believe there exists one, and if one existed, it would not be a common word. (Even サイトトランスレーション itself is not such a common word yet like 翻訳 and 通訳)
In case you absolutely had to choose between 翻訳 and 通訳 for some reason, you would choose 翻訳 because 通訳 always involves three parties --- two in need of communicating with each other and the interpreter.